You need to decide whether you mean 4x - y = -7 or 4(x - y = -7.
I will get you started on the first meaning; you should be able to finish or to solve it with the other meaning.
4x - y = -7
x + 2y = -4
Multiply the first equation by 2
8x - 2y = -14
x + 2y = -4
Add
9x = -18
You take it from here.