Method 1: Algebraically find f(g(x)) first and then plug in x = 5 f(x) = 6x+3 f(g(x)) = 6*[ g(x) ] + 3 f(g(x)) = 6*(x-4) + 3 f(g(x)) = 6x-24+3 f(g(x)) = 6x-21 f(g(5)) = 6*5-21 f(g(5)) = 9
OR
Method 2: Find g(5) first and plug that into x of f(x) g(x) = x-4 g(5) = 5-4 g(5) = 1 So f(g(5)) is equivalent to f(1) f(x) = 6x+3 f(1) = 6*1+3 f(1) = 9