A manufacturer wishes to make tee-shirts for the band Indigo Girls. They sell for $18 each. She must deliver all the tee-shirts in 20 days time. The manufacturer will first 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 shirts in one day. All the machines must be set up before any of them are turned on. Express the total amount of money M she will receive for the shirts in terms of the number n of machines she decides to set up (assuming she sells all the shirts she makes).