3x + 8(x + 9) = -5
3x + 8x + 72 = -5
11x + 72 = -5
11x + 72 - 72 = -5 - 72
11x = -77
11x/11 = -77/11
x = -7
All you have to do for this equation is to substitute the y in the second equation with what y equals to. Then you distribute and combine like-terms.
