A pool membership during the summer costs $7 per week. The total cost of a membership is given by
f(x) = 7x. The pool also rents out lockers for $2 per week. The
total cost of a membership and a rental is given by g(x) = 9x.
What is the difference between a 12-week membership
if you get a locker and if you don't? Explain how you
got your answer.