Question

2x – y = 5
3x – 2y = 12

Answer 1

y=-9
x=-2

Answer 2

Make the two equations equivalent to each other...in this case, instead of 2x - y = 5, you move the 5 over and get (2x - y + 5)...and instead of 3x - 2y = 12, you get (3x - 2y - 12).
Now you can say (2x - y + 5) = (3x - 2y - 12). Now solve:
1. 2x - y + 5 MINUS 5 = 3x - 2y - 12 MINUS 5
2. 2x - y = 3x - 2y - 17. Now add 2y to both sides.
2a. 2x - y PLUS 2y = 3x - 2y PLUS 2y - 17
3. 2x + y = 3x - 17. Now subtract 2x from both sides.
3a. 2x MINUS 2x + y = 3x MINUS 2x - 17.
4. y = x - 17.

I'm not sure if they want actual amounts for x and y, but this relationship (y is 17 greater than x) is constant. I'm assuming you're solving for the equation for a line.