Explanation:
your answers for a. are correct.
b.
(f○g)(x) = f(g(x))
that means we are using the expression of g(x) as input to f(x). so, for f(x), x turns into g(x) = 0.9x
(f○g)(x) = f(g(x)) = 0.9x - 220
what it does is it reduces the price by 10% and then gives on to of that an additional absolute value discount if $220.