Answer:
x = 3, y = -1
Explanation:

To solve this, we will eliminate x. In order to do this, we must multiply the bottom equation by 2:

To eliminate x, we will subtract the bottom equation from the top one:

Divide both sides by -7:
-7y/-7 = 7/-7
y = -1
Substitute this into the first equation:
4x-3(-1) = 15
4x--3 = 15
4x+3 = 15
Subtract 3 from each side:
4x+3-3 = 15-3
4x = 12
Divide both sides by 4:
4x/4 = 12/4
x = 3