You have the following equation:
-8 + (x/7) = -10
in order to solve the previous equation, proceed as follow:
-8 + (x/7) = -10 add 8 both sides
x/7 = -10 + 8 simplify right side
x/7 = -2 multiply by 7 both sides
x = -2(7)
x = -14
hence, the solution to the given equation is x=-14