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