You have the following equation:
5 = (7 - y)/9
in order to solve the previous equation, proceed as follow:
5 = (7 - y)/9 multiply both sides by 9
45 = 7 - y subtract 7 both sides
45 - 7 = -y simplify left side
38 = -y
y = -38
Hence, the solution to the given equation is y = -38
