Question

When solving the system x + 2y = 9 and x - y = 6, which expression could be substituted for x in the second equation?
A. 9 - x
B. y - 9/2
C. 9 - 2y
D. 1/2 y + 9

Answer 1

B.

Answer 2

well first you have to get x to equal something in the first equation, we can do that by subtracting 2y from both sides to get the x alone. it should look like
x=9-2y
so C is your answer