Answer:
ƒ(g(x)) = 18x - 8
Explanation:
We're looking for the composition of f and g, in which function g is the input to function f. Literally replace "x: in f(x) with g(x) = 6x - 5:
ƒ(g(x)) = 3(6x - 5) + 7, or, after simplification,
ƒ(g(x)) = 18x - 15 + 7, or 18x - 8