Final answer:
The total cost of the shoes after applying a $15 coupon and a 20% discount on the reduced price is represented by the function g(f(x)) = 0.8 × (x - 15), which is option A).
Step-by-step explanation:
The problem involves applying a $15 coupon to the original cost of the shoes and then applying a 20% member discount. To represent this mathematically, we define two functions: one for applying the coupon (let's call it f(x)) and another for applying the discount (g(x)). If x represents the original price, the coupon is applied first, so we have f(x) = x - 15. Then a 20% discount is applied to the new amount, which is represented by g(f(x)) = 0.8 × (f(x)). Substituting f(x) into g(f(x)), we get g(f(x)) = 0.8 × (x - 15), which is option A).