the manager of a carwash must decide whether to have 1 or 2 wash lines. 1 line will mean a fixed cost of $6000/month and 2 lines will mean a fixed cost of $10,500/month. each line would be able to process 15 cars/hour. variable costs will be $3/car, and revenue will be $5.95/car. the manager projects an average demand of between 14 and 18 cars an hour. would you reccomend 1 or 2 lines? explain. also, the car wash is open 300 hours a month.