Carlo and Anita make mailboxes and toys in their craft shop near Lincoln. Each mailbox requires 1 hour of work from Carlo and 3 hours from Anita. Each toy requires 1 hour of work from Carlo and 1 hour from Anita. Carlo cannot work more than 7 hours per week and Anita cannot work more than 16 hours per week. If each mailbox sells for $14 and each toy sells for $21, then how many of each should they make to maximize their revenue? What is their maximum revenue?