Question

What is the y-coordinate of the solution for the system of equations?

Answer 1

First equation is: x - y = 12
x = 12 + y

Now, substitute this in 2nd equation, 
2x - 3y = 27
2(12+y) - 3y = 27
24 + 2y - 3y = 27
-y = 27 - 24
y = -3

In short, Your Answer would be -3

Hope this helps!