7x + y = - 9 implies that y = -9 - 7x
Sub this into the second equation for y and we get that
-x - 2( -9 - 7x) = 5 simplify
-x + 18 + 14x = 5
13x + 18 = 5 subtraact 18 from both sides
13x = -13 divide both sides by 13
x = -1
And
y = - 9 - 7(-1) = -9 + 7 = -2
+20 
