The first you can multiply first equation by 2, you will get 16x - 12y = - 40, then add first equation to second
16x - 12y - 16x + 7y = - 40 + 30
-5y = - 10
Y= 2;
Then put y to first equation, because it easier.
8x - 2*6=-20
8x = - 8
X= - 1
Answer is x = - 1, y = 2.