You have the following equation:
-3y - 6 - 7y = 14
in order to solve the previous equation, proceed as follow:
-3y - 6 - 7y = 14 simplify left side like terms
-10y - 6 = 14 add 6 both sides
-10y = 14 + 6
-10y = 20 divide by -10 both sides
y = 20/(-10)
y = -2
Hence, the solution to the given equation is y = -2