Which equation combines with the given equation solution x = 3 and y = 9? X + 2y = 21 A. 4x + 6y = 64 B. 2x + y = 36 C. 4x + y = 21 D. -3x + 4y = 33 E. 3x + 2y = 28

C. 4x + y = 21

Step-by-step explanation:

X + 2y = 21

A. 4x + 6y = 64

B. 2x + y = 36

C. 4x + y = 21

D. -3x + 4y = 33

E. 3x + 2y = 28

x = 3

y = 9

X + 2y = 21

3 + 2(9) = 21

3 + 18 = 21

21 = 21

A. 4x + 6y = 64

4(3) + 6(9) = 64

12 + 54 = 64

66 is not = 64

B. 2x + y = 36

2(3) + 9 = 36

6 + 9 = 36

15 is not = 36

C. 4x + y = 21

4(3) + 9 = 21

12 + 9 = 21

21 = 21

c. y = 1/4 x + 5

step-by-step explanation:

first, put the equation of the line on the graph into slope-intercept form

(y = mx + b):   y = -4x + 8

second, a perpendicular line has to have "an opposite/reciprocal slope" to the original slope. so, find the "m" value in your original equation (it's -4, right? )

original slope: m = -4   perpendicular slope: change the sign to its opposite and find the reciprocal ("flip" the number)

new slope is now positive (b/c the original slope was negative 4), and it's 1/4 (not the original slope of 4 or 4/1)

answer: 94

step-by-step explanation: 79+91+92+94+94 = 450 divided by 5 (since there are 5 number that are being added) = 90