A manager must decide how many machines of a certain type to purchase. Each machine can process 100 customers per day. One machine will result in a fixed cost of $2,100 per day, while two machines will result in a fixed cost of $3,700 per day. Variable costs will be $16 per customer, and revenue will be $45 per customer. a. Determine the break-even point for each range. (Round your answers to the next whole number.) b. If estimated demand is 90 to 120 customers per day, how many machines should be purchased