Tire manager of a car wash must decide whether to have one or two wash lines. One line will have a fixed cost of $4,000 a month, and two lines will have a fixed cost of $7,000 a month. Each line would be able to process 15 cars an hour. Variable costs will be$I per car, and revenue will be $3 per car. The manager projects average demand of between 14 and 18 cars an hour. Would you recommend one or two lines? The car wash will be open 300 hours a month.