Quote: what is the answer to 4x-7y=3
x-7y=-15
First you set the two on top of each other so you can visualize them better
4x -7y = 3
x -7y = -15
now since you have -7y in both you can subtract the 2nd equation from the first one to get
(4x - x) + (-7y -(-7y)) = 3 - (-15)
3x = 18
x = 6
and just plug this back into either equation, I'll use the first one
4(6) - 7y = 3
24 - 7y = 3
21 = 7y
y=3
and your solution is thus
x=6, y=3
+6251 
