Carlo and Anita make mailboxes and toys in their craft shop near Lincoln. Each mailbox requires 4 hours of work from
Carlo and 4 hours from Anita. Each toy requires 2 hours of work from Carlo and 4 hours from Anita. Carlo cannot work
more than 20 hours per week and Anita cannot work more than 28 hours per week. If each mailbox sells for $15 and
each toy sells for $24, then how many of each should they make to maximize their revenue? What is their maximum
revenue?