A manufacturer wishes to make tee-shirts for the band Indigo Girls. They sell for 12 dollars each. She must deliver all the tee-shirts in 20 days time. The manufacturer will rst set up some machines. Once all machines are set up she will turn them on. Each machine takes one day to set up. A machine produces 200 teeshirts in one day. All the machines must be set before any of them are turned on. a. Express the amount of money she will receive for the shirts in terms of the number of machines in she decides to set up. t: b. Use calculus to nd out how many machines she should set up to obtain the most money. m