Answer:
x = 19
Step-by-step explanation:
The angles are vertical angles which means they are equal
3x-3 = 6(x-10)
Distribute
3x-3 = 6x-60
Subtract 3x from each side
3x-3 -3x = 6x-60-3x
-3 =3x-60
Add 60 to each side
-3+60 =3x-60+60
57 = 3x
Divide by 3
57/3 = 3x/3
19 =x
The height of a right cylinder is 3 times the radius of the base. The volume of the cylinder is 249 cubic units.
What is the height of the cylinder?
O2 units
4 units
O 6 units
O 8 units
Answer:
h = 6 unitsStep-by-step explanation:
Volume of a cylinder = πr²h
where r is the radius
h is the height
The height of a right cylinder is 3 times the radius of the base is written as
h = 3r
Volume = 249cubic units
So we have
249 = π r²(3r)
249 = π3r³
Divide both sides by 3π
r³ = 249/3π
r = 2
h = 3(2)
h = 6 units
Hope this helps you
what is this? 15.8 = d/25
Answer:
395
Step-by-step explanation:
15.8=d/25
multiply both sides by 25 to remove the denominator
25×15.8=d
d=395
anyone know how to do this. im hella lost right now
Answer:
a=6
b=5.5
Step-by-step explanation:
not very sure but..
since 8X2=16,
a=3X2
b=11/2
Please help me. The function g(x) is a transformation of f(x). If g(x) has a y-intercept at 3, which of the following functions could represent g(x)?
The graph shows f(x) to have a y intercept at -1, which is where the diagonal line crosses the y axis. We want the y intercept to move to 3. So we must add 4 to the old y intercept to get the new y intercept.
We do this with every single point on f(x) to get g(x) = f(x)+4. This shifts the graph up 4 units.
Identify the correct HYPOTHESES used in a hypothesis test of the following claim and sample data:
Claim: "The average battery life (between charges) of this model of tablet is at least 12 hours."
A random sample of 80 of these tablets is selected, and it is found that their average battery life is 11.58 hours with a standard deviation of 1.93 hours. Test the claim at the 0.05 significance level.
a. H0: p = 12 vs. H1: p < 12
b. H0: ? = 12 vs. H1: ? < 12
c. H0: p = 12 vs. H1: p > 12
d. H0: ? = 12 vs. H1: ? > 12
Answer:
The null hypothesis is ;
H0 ≥ 12
While the alternative hypothesis H1 is ;
H1 < 12
Step-by-step explanation:
Here, we want to correctly identify the null hypothesis H0 and the alternative hypothesis H1
The null hypothesis is as follows ;
H0 ≥ 12
While the alternative hypothesis H1 is ;
H1 < 12
What is the rule of 72 used to determine? A. the approximate time it takes an investment to triple in value B. the approximate time it takes an investment to double in value C. the approximate time it takes to earn 10% interest D. the approximate time it takes to earn $72 on any investment amount
Answer:
b. the approx time it takes an investment to double in value
You work at a coffee house. Roasted coffee beans retain approximately 3/5 of their initial weight. Approximately what percent of their inital weight do they retain?
Answer:
60%
Step-by-step explanation:
We need convert 3/5 into a percent in order to find the answer.
We can convert by first dividing 3 by 5 to find the decimal value.
3/5= .6
Now we need to multiply by 100 to make it a percentage
.6 x 100= 60
60%
please factor!
7x^2+27xy-4y^2
PLEASE HELP ?
Convert by looking at the thermometer and measure to the nearest 5 degrees F.
31 degrees Celsius to Fahrenheit
Answer:
90º
Step-by-step explanation:
just look at where 31º on the right lines up with the value on the left (aka around 90º)
Answer:
87.8 °F ≈ 90°F
Step-by-step explanation:
[tex]x \ degrees \ F = 31 \ degree \ Celsius *\frac{9}{5} + 32\\x \ degrees \ F = 55.8 + 32\\\\x \ degrees \ Fahrenheit = 87.8 \ degrees \ Farenheit[/tex]
21. In the figure given below, AC is parallel to DE. Find the valuesof xy and z and hence find the 2DBE.
21-70X
509
Answer:
X= 50°
Y= 70°
Z= 30°
BDE= 30°
2BDE= 60°
Step-by-step explanation:
(2x -70 )+z+(2x+20)=180...(sum of angle on a straight line)
2x -70 = BDE... alternate angles
Y + (2x-70)+(50+x-20) = 180...(sum of angles in a triangle)
X-20 = z ... alternate and opposite angles
(2x -70 )+z+(2x-+20)=180
2x-70 + x-20 +2x +20= 180
5x -70= 180
5x = 250
X= 50°
X-20 = z
50-20= z
30° = z
2x -70 = BDE
2(50) -70 = BDE
100-70 = BDE
30°= BDE
Y + (2x-70)+(50+x-20)
Y + 100-70 +50 +50 -20 = 180
Y + 200-90=180
Y= 70°
2BDE = 2*30
2BDE= 60°
The sum of Jason’s age and his brother’s age is 55. Jason is 7 years younger than his brother. How old is Jason?
Answer:
Jason is 24 years old
Step-by-step explanation:
Lets say that Jason's age is X, and his brother's age is Y.
We know that X + Y = 55.
We also know that (X + 7) = Y.
This means (X + 7) + Y = 62 (We got the 62 by adding 55 and 7)
Anyway if X+7= Y, and X+7 + Y = 62, then X+7 = 62/2, right?
We divide the 62 by 2 and we get 31.
Alright, so X+7 = 31.
substract both sides by 7.
We get X = 24
Sorry if this seemed longer or more complicated than it should've been, I don't know how to explain it better.
Sanjay makes souvenir pyramids by pouring liquid into a pyramid-shaped mold. The mold he uses has a square base with a side length of 10\text{ cm}10 cm10, start text, space, c, m, end text, and the height of the mold is 10\text{ cm}10 cm10, start text, space, c, m, end text. Sanjay wants to make a smaller pyramid using the same mold, so he plans to fill the mold 2\text{ cm}2 cm2, start text, space, c, m, end text from the top. What is the approximate volume of this smaller pyramid?
Answer:
170.67
Step-by-step explanation:
Answer:
171
Step-by-step explanation:
Modeling the situation
If we fill the pyramid mold 2\text{ cm}2 cm2, start text, space, c, m, end text from the top, we have a smaller pyramid that's similar to the original pyramid.
Since the pyramids are similar, we can set up a proportional equation to find the side lengths and height of the smaller pyramid, and then find its volume.
Hint #22 / 4
Base and height of smaller pyramid
The height of the smaller pyramid is 10-2=8\text{ cm}10−2=8 cm10, minus, 2, equals, 8, start text, space, c, m, end text.
We can solve for the length \blueE{\ell}ℓstart color #0c7f99, ell, end color #0c7f99 in the smaller pyramid using a proportional equation.
\begin{aligned} \dfrac{\blueE{\ell}}{10} &= \dfrac{8}{10} \\\\ \blueE{\ell} &= \blueE{8} \end{aligned}
10
ℓ
ℓ
=
10
8
=8
Hint #33 / 4
Volume of smaller pyramid
\begin{aligned} \text{volume}_{\text{pyramid}} &= \dfrac13(\text{base area})(\text{height}) \\\\ &= \dfrac13 \cdot (\blueE{\ell})^2\cdot (\text{height}) \\\\ &= \dfrac13 \cdot \blueE{8}^2\cdot(8)\\\\ &= \dfrac{512}{3}=170.\overline{6}\\\\ &\approx \purpleD{170.67} \end{aligned}
volume
pyramid
=
3
1
(base area)(height)
=
3
1
⋅(ℓ)
2
⋅(height)
=
3
1
⋅8
2
⋅(8)
=
3
512
=170.
6
≈170.67
Hint #44 / 4
To the nearest cubic centimeter, the volume of the smaller pyramid is about 171\text{ cm}^3171 cm
3
171, start text, space, c, m, end text, cubed.
Write the equation of the line in slope intercept form that passes through the points (4,-2) and (2,-1)
Answer:
y + 2 = (-1/2)(x - 4)
Step-by-step explanation:
Let's move from (2, -1) to (4, -2) and measure the changes in x and y. x increases by 2 units from 2 to 4, and y decreases by 1 unit from -1 to -2. Thus, the slope of the line connecting the two points is m = rise / run =
-1
--- = (-1/2).
2
Using the point-slope formula, we get:
y + 2 = (-1/2)(x - 4)
Fake Question: Should Ujalakhan01 be a moderator? (If you could answer I'd appreciate it haha.)
Real Question: Simplify [tex](a^5*a^4)+(b^2*b^3)-(c^7*c^6)[/tex]
Answer:
[tex]a^9 + b^ 5 + c^{13}[/tex]
Step-by-step explanation:
[tex](a^5 \times a^4)+(b^2 \times b^3) + (c^7 \times c^6)[/tex]
When bases are same and it is multiplication, then add the exponents.
[tex](a^{5+4})+(b^{2+3})+(c^{7+6})[/tex]
[tex](a^9)+(b^ 5) + (c^{13})[/tex]
Apply rule : [tex](a^b)=a^b[/tex]
[tex]a^9 + b^ 5 + c^{13}[/tex]
Answer:
[tex]a^9+b^5-c^{13[/tex]
Step-by-step explanation:
[tex](a^5*a^4) + (b^2*b^3)-(c^7*c^6)[/tex]
When bases are same, powers are to be added.
=> [tex](a^{5+4})+(b^{2+3})-(c^{7+6})[/tex]
=> [tex]a^9+b^5-c^{13[/tex]
One kind of candy (jelly) sells for $5 a pound and another (chocolate) for $10 a pound. How many pounds of each should be used to make a mixture of 10 pounds of candy (both kinds) that sells for a total $80 (i.e. $8/pound)?
Answer:
chocolate: 6 poundsjelly: 4 poundsStep-by-step explanation:
Let x represent the number of pounds of chocolate in the mix. Then the total price of 10 pounds of mix is ...
10x +5(10 -x) = 80
5x +50 = 80
5x = 30
x = 6 . . . . . . . . pounds of chocolate
10 -x = 4 . . . . . pounds of jelly candy
6 pounds of chocolate and 4 pounds of jelly should be used to make the mixture.
Please help me with this!
Answer:
5:1
Step-by-step explanation:
20/4= 5
1*5 = 5
5:1 ratio
Hope this helps!
Hi I need this question please asap.
The amount of time to complete a physical activity in a PE class is approximately normally normally distributed with a mean of 32.9 seconds and a standard deviation of 6.4 seconds.
A) What is the probability that a randomly chosen student completes the activity in less than 33.2 seconds?
B) What is the probability that a randomly chosen student completes the activity in more than 46.6 seconds?
C) What proportion of students take between 35.5 and 42.8 seconds to complete the activity?
D) 75% of all students finish the activity in less than____seconds.
Answer:
The answer is below
Step-by-step explanation:
Given that mean (μ) of 32.9 seconds and a standard deviation (σ) of 6.4 seconds.
The z score is used to measure by how many standard deviation the raw score is above or below the mean. It is given by:
[tex]z=\frac{x-\mu}{\sigma}\\[/tex]
a) For x < 33.2 seconds
[tex]z=\frac{x-\mu}{\sigma}\\\\z=\frac{33.2-32.9}{6.4} =0.05[/tex]
From the normal distribution table, the probability that a randomly chosen student completes the activity in less than 33.2 seconds = P(x < 33.2) = P(z < 0.05) = 0.5199 = 51.99%
b) For x > 46.6 seconds
[tex]z=\frac{x-\mu}{\sigma}\\\\z=\frac{46.6-32.9}{6.4} =2.14[/tex]
From the normal distribution table, the probability that a randomly chosen student completes the activity in more than 46.6 seconds = P(x > 46.6) = P(z > 2.14) = 1 - P(z < 2.14) = 1 - 0.9927 = 0.0073 = 0.73%
c) For x = 35.5 seconds
[tex]z=\frac{x-\mu}{\sigma}\\\\z=\frac{35.5-32.9}{6.4} =0.41[/tex]
For x = 42.8 seconds
[tex]z=\frac{x-\mu}{\sigma}\\\\z=\frac{42.8-32.9}{6.4} =1.55[/tex]
From the normal distribution table, the proportion of students take between 35.5 and 42.8 seconds to complete the activity = P(35.5 < x < 42.8) = P(0.41< z< 1.55) = P(z < 1.55) - P(z < 0.41) = 0.9332 - 0.6591 = 0.2741 = 27.41%
d) A probability of 75% = 0.75 corresponds to a z score of 0.68
[tex]z=\frac{x-\mu}{\sigma}\\\\0.68=\frac{x-32.9}{6.4} \\\\x-32.9=4.4\\x=4.4+32.9\\x=37.3[/tex]
75% of all students finish the activity in less than 37.3 seconds
The exact heights of different elephants Choose the correct answer below. A. The data are continuous because the data can only take on specific values. B. The data are discrete because the data can take on any value in an interval. C. The data are discrete because the data can only take on specific values. D. The data are continuous because the data can take on any value in an interval.
Answer:
Option d: The data are continuous because the data can take on any value in an interval.
Step-by-step explanation:
The data are continuous if they can take on any value within a range. In this case study, there are different elephants including small/young ones and big ones/old ones.
Thus, their heights will vary and can take on any value within a particular range.
Find the probability of each event. A six-sided die is rolled seven times. What is the probability that the die will show an even number at most five times?
Answer:
[tex]\dfrac{15}{16}[/tex]
Step-by-step explanation:
When a six sided die is rolled, the possible outcomes can be:
{1, 2, 3, 4, 5, 6}
Even numbers are {2, 4, 6}
Odd Numbers are {1, 3, 5}
Probability of even numbers:
[tex]\dfrac{\text{Favorable cases}}{\text{Total cases }} = \dfrac{3}{6} = \dfrac{1}{2}[/tex]
This is binomial distribution.
where probability of even numbers, [tex]p =\frac{1}{2}[/tex]
Probability of not getting even numbers (Getting odd numbers) [tex]q =\frac{1}{2}[/tex]
Probability of getting r successes out of n trials:
[tex]P(r) = _nC_r\times p^r q^{n-r}[/tex]
Probability of getting even numbers at most 5 times out of 7 is given as:
P(0) + P(1) +P(2) + P(3) +P(4) + P(5)
[tex]\Rightarrow _7C_0\times \frac{1}{2}^0 \frac{1}{2}^{7}+_7C_1\times \frac{1}{2}^1 \frac{1}{2}^{6}+_7C_2\times \frac{1}{2}^2 \frac{1}{2}^{5}+_7C_3\times \frac{1}{2}^3 \frac{1}{2}^{4}+_7C_4\times \frac{1}{2}^4 \frac{1}{2}^{3}+_7C_5\times \frac{1}{2}^5 \frac{1}{2}^{2}[/tex]
[tex]\Rightarrow (\dfrac{1}{2})^7 (_7C_0+_7C_1+_7C_2+_7C_3+_7C_4+_7C_5)\\[/tex]
[tex]\Rightarrow (\dfrac{1}{2})^7 (1+7+\dfrac{7 \times 6}{2}+\dfrac{7 \times 6 \times 5}{3\times 2}+\dfrac{7 \times 6 \times 5}{3\times 2}+\dfrac{7 \times 6}{2})\\\Rightarrow \dfrac{120}{128} \\\Rightarrow \dfrac{15}{16}[/tex]
Simba Travel Agency arranges trips for climbing Mount Kilimanjaro. For each trip, they charge an initial fee of $100 in addition to a constant fee for each vertical meter climbed. For instance, the total fee for climbing to the Shira Volcanic Cone, which is 3000 meters above the base of the mountain, is $400.Let y represent the total fee (in dollars) of a trip where they climbed x vertical meters.Complete the equation for the relationship between the total fee and vertical distance.
Answer:
[tex]y(x)=100+0.1x[/tex]
Step-by-step explanation:
Let y represent the total fee (in dollars) of a trip where they climbed x vertical meters.
We know that there is an initial fee of $100, so we know that if we climb x=0 meters, we have a fee of y(0)=100.
[tex]y(0)=100[/tex]
As there is a constant fee (lets called it m) for each vertical meter climbed, we have a linear relationship as:
[tex]y(x)-y(0)=m(x-0)\\\\\\y(x)-100=mx\\\\\\y(x)=100+mx[/tex]
We know that for x=3000, we have a fee of $400, so if we replace this in the linear equation, we have:
[tex]y(3000)=100+m(3000)=400\\\\\\100+3000m=400\\\\3000m=400-100=300\\\\m=300/3000=0.1[/tex]
Then, we have the equation for the total fee in function of the vertical distance:
[tex]y(x)=100+0.1x[/tex]
I hope u can understand help asap
i think u can see sho T=5n+20
Answer:
T(n) = 5n + 20
Step-by-step explanation:
1 candy has a mass of 5 g.
n candies have a mass of 5n grams.
The box has a mass of 20 grams.
total mass = mass of candies + mass of box
T(n) = 5n + 20
n T(n)
0 20
25 145
50 270
75 395
100 520
An article in Fire Technology, 2014 (50.3) studied the effectiveness of sprinklers in fire control by the number of sprinklers that activate correctly. The researchers estimate the probability of a sprinkler to activate correctly to be 0.7. Suppose that you are an inspector hired to write a safety report for a large ballroom with 10 sprinklers. Assume the sprinklers activate correctly or not independently. (a) What is the probability that all of the sprinklers will operate correctly in a fire
Answer:
probability that all of the sprinklers will operate correctly in a fire: 0.0282
Step-by-step explanation:
In order to solve this question we will use Binomial probability distribution because:
In the question it is given that the sprinklers activate correctly or not independently. The number of outcomes are two i.e. sprinklers activate correctly or not.A binomial distribution is a probability of a success or failures outcomes in an repeated multiple or n times.
Number of outcomes of this distributions are two.
The formula is:
b(x; n, P) = [tex]C_{n,x}*p^{x} * (1 - p)^{n-x}[/tex]
b = binomial probability also represented as P(X=x)
x =no of successes
P = probability of a success on a single trial
n = no of trials
[tex]C_{n,x}[/tex] is calculated as:
[tex]C_{n,x}[/tex] = n! / x!(n – x)!
= 10! / 10!(10-10)!
= 1
According to given question:
probability of success i.e. p = 0.7 i.e. probability of a sprinkler to activate correctly.
number of trials i.e. n = 10 as number of sprinklers are 10
To find: probability that all of the sprinklers will operate correctly in a fire
X = 10 because we have to find the probability that "all" of the sprinklers will operate correctly and there are 10 sprinklers so all 10 of them
So putting these into the formula:
P(X=x) = [tex]C_{n,x}*p^{x} * (1 - p)^{n-x}[/tex]
= C₁₀,₁₀ * 0.7¹⁰ * (1-0.7)¹⁰⁻¹⁰
= 1 * 0.0282 * (0.3) ⁰
= 1 * 0.0282 * 1
P(X=x) = 0.0282
what’s the opposite of negative two
Answer: The answer is two
Step-by-step explanation: If you look for opposites of a number its either negative or positive. So when the answer is negative, the opposite is positive and if the answer is positive, the opposite is negative.
Answer:
[tex]\boxed{2}[/tex]
Step-by-step explanation:
The opposite of a number is the number that is the same distance from 0 on the number line.
-2 opposite is 2.
2. Compare the function ƒ(x) = –x^2 + 4x – 5 and the function g(x), whose graph is shown. Which function has a greater absolute maximum (vertex)?
Answer:
g(x)
Step-by-step explanation:
The vertex of g(x) as shwon in the graph is located in the point wich coordinates are (3.5,6.25) approximatively
We need to khow the coordinates of f(x) vertex
Here is a way without derivating:f(x) = -x² + 4x -5
let a be the leading factor, b the factor of x and c the constant:
a= -1b= 4c= -5The coordinates of a vertex are: ([tex]\frac{-b}{2a}[/tex] , f([tex]\frac{-b}{2a}[/tex]) )
-b/2a = -4/ (-1*2) = 4/2 = 2
f(2)= -2²+4*2-4 = -4+4-4 = -4
obviosly f(x) has a minimum wich less than g(x)'s maximum
Answer:
Step-by-step explanation:
g(x) i think
A certain virus infects one in every 400 people. A test used to detect the virus in a person is positive 80% of the time if the person has the virus and 10% of the time if the person does not have the virus. (This 10% result is called a false positive.) Let A be the event "the person is infected" and B be the event "the person tests positive".
(a) Using Bayes’ Theorem, when a person tests positive, determine the probability that the person is infected.
(b) Using Bayes’ Theorem, when a person tests negative, determine the probability that the person is not infected.
Answer:
A) P(A|B) = 0.01966
B) P(A'|B') = 0.99944
Step-by-step explanation:
A) We are told that A is the event "the person is infected" and B is the event "the person tests positive".
Thus, using bayes theorem, the probability that the person is infected is; P(A|B)
From bayes theorem,
P(A|B) = [P(A) × P(B|A)]/[(P(A) x P(B|A)) + (P(A') x P(B|A'))]
Now, from the question,
P(A) = 1/400
P(A') = 399/400
P(B|A) = 0.8
P(B|A') = 0.1
Thus;
P(A|B) = [(1/400) × 0.8)]/[((1/400) x 0.8) + ((399/400) x (0.1))]
P(A|B) = 0.01966
B) we want to find the probability that when a person tests negative, the person is not infected. This is;
P(A'|B') = P(Not infected|negative) = P(not infected and negative) / P(negative) = [(399/400) × 0.9)]/[((399/400) x 0.9) + ((1/400) x (0.2))] = 0.99944
Ash Lee bought a new Brunswick boat for $17,000. He made a $2,500 down payment on it. The bank's loan was for 60 months. Finance charges totaled $4,900. His monthly payment is:
Answer: $323.33
Step-by-step explanation:
($17,000 + $4,900 - $2,500) ÷ 60 months = $323.33 per month
↓ ↓ ↓
price finance down payment
Alex has built a garden shed in the shape shown.
(A) Alex plans to paint the outside of the shed, including the roof but not the floor. One can of paint can cover 6m^2 . How many cans of paint will Alex need.
(B)If one can of paint costs $25.50, what will the cost be including 13% tax.
Answer:
A) 22 cans required to paint
B) Including 13% tax, cost of painting = $633.93
Step-by-step explanation:
As we check the figure, we have a composite figure.
Cuboid on the base and a pyramid on the top of it.
To find the area to be painted, we have 4 rectangular faces of cuboid with dimensions 6m [tex]\times[/tex] 3m.
And 4 triangular faces of pyramid with Base = 6m and Height 5m.
So, total area to be painted = 4 rectangular faces + 4 triangular faces
Area of rectangle = Length [tex]\times[/tex] Width = 6 [tex]\times[/tex] 3 = 18 [tex]m^2[/tex]
Area of triangle = [tex]\frac{1}{2}\times Base \times Height =\frac{1}{2}\times 6 \times 5 = 15\ m^{2}[/tex]
Total area to be painted = 4 \times 18 + 4 \times 15 = 72 + 60 = 132 [tex]m^2[/tex]
A) Area painted by 1 can = 6 [tex]m^2[/tex]
Cans required to paint 132 [tex]m^2[/tex] = [tex]\frac{132}{6} = 22\ cans[/tex]
B)
Cost of 1 can = $25.50
Cost of 22 can = $25.50 [tex]\times[/tex] 22 = $561
Including tax of 13% = $561 + $561 [tex]\times \frac{13}{100}[/tex] = $561 + $72.93 = $633.93
So, the answers are:
A) 22 cans required to paint
B) Including 13% tax, cost of painting = $633.93
A train travels 45 feet in 1/10 if a second. How far will it travel in 3.5 seconds
Answer:
1575 ft
Step-by-step explanation:
Convert 1/10 to decimal to make the math simpler.
1/10 = 0.1
Divide 3.5 by 0.1.
3.5/0.1 = 35
Multiply 35 by 45.
35 × 45 = 1575
The train will travel 1575 feet in 3.5 seconds.
The distance covered by the train in 3.5 seconds will be 1575 feet.
What is speed?The distance covered by the particle or the body in an hour is called speed. It is a scalar quantity. It is the ratio of distance to time.
We know that the speed formula
Speed = Distance/Time
A train travels 45 feet in 1/10 in a second.
Then the speed will be
Speed = 45 / (1/10)
Speed = 45 x 10
Speed = 450 feet per second
The distance covered by the train in 3.5 seconds will be
Distance = 450 x 3.5
Distance = 1575 feet
More about the speed link is given below.
https://brainly.com/question/7359669
#SPJ2
A system of equations is shown below: Equation A: 3c = d − 8 Equation B: c = 4d + 8 Which of the following steps should be performed to eliminate variable d first?
Answer:
multiplying the equation A
Step-by-step explanation:
3c=d-8 ####### *4
+ c=4d + 8
After that you will get the value of c and d.
Answer:
Multiply equation A by -4
Step-by-step explanation:
3c = d - 8
c = 4d + 8
Multiply equation A by -4.
-12c = -4d + 32
c = 4d + 8
Add the equations.
-11c = 40
Variable d is eliminated.