Question

I need a step-by-step process on how to do:

-3x+y=9
y=x-7

I would think this is a substitution problem.

Answer 1

x = -8

y = -15

Explanation:

-3x + y = 9

y = x - 7

-3x + x - 7 = 9

-2x - 7 = 9

-2x = 16

2x = -16

x = -8

y = -8 - 7

y = -15