Check these answers? ?

Question

3x + y = -8
My answer: y=-11

2x - y = 11
My Answer: y=13

Answer 1

3x + y = -8

y = -8 -3x

2x - y = 11

y= 2x - 11

Answer 2

Thank you so much! How did you get those though? I cant seem to figure it out...