solving systems of equations subtraction

Question

6x-y=-4
2x+2y=15

Answer 1

double the first:
12x - 2y = -8
2x+ 2y = 15
add them:
14x = 7
x = 1/2

sub into 6x - y = -4
3 - y = -4
-y = -7
y = 7