Please explain: f'(x) = f'(g(x)) * g'(x) Note: f'(g(x)) = 3g(x)^2. You can then substitute 5 for x and simplify.? I have solved and got 75 that is wrong, 30 is wrong, and 225 is wrong. Can someone please explain how to solve?

Arestaurant offers delivery for their pizzas. the total cost the customer pays is the price of the pizzas, plus a delivery fee. one customer pays $23 to have 2 pizzas delivered. another customer pays $59 for 6 pizzas. how many pizzas are delivered to a customer who pays $86?