Step-by-step explanation:
In this equation, given
f(x) = 3x + 9 and g(x) = 5x -1
So the question is what is the value of f if we put the value of g(x) in f(x)
So to solve the equation we need to replace the value of x in f(x) with g(x)
So it was obtained as below
f(g(x)) = 3(5x-1) + 9
= (15 x - 3) + 9
= 15 x + 6