Question

Graph the system by using technology. What is the y-coordinate of the solution?

Answer 1

Take second equation here, 
2x + 9 = -12
2x = -12 - 9
2x = -21
Multiply by 2, 
4x = -42

Now, substitute the vaue of 4x in 1st equation, 
-42 - y = 2
-y = 2 + 42
y = -44

In short, Your Answer would be -44

Hope this helps!