A small manufacturing firm produces two microwave switches, switch A and switch B. Each switch passes through two departments: assembly and testing. Switch A requires 4 hours of assembly and 1 hour of testing, while switch B requires 3 hours of assembly and 2 hours of testing. The maximum hours available each week for assembly and testing are 240 hours and 140 hours, respectively. The profit earned for switch A is $20 each and the profit earned for switch B is $30 each. How may switches of each type should be produced in order to maximize profit? What is the maximum profit?