The manager of a car wash must decide whether to have one or two wash lines. one line will mean a fixed cost of $5,900 a month, and two lines will mean a fixed cost of $10,620 a month. each line would be able to process 15 cars an hour. variable costs will be $4 per car, and revenue will be $5.95 per car. the manager projects an average demand of between 14 and 18 cars an hour. would you recommend one or two lines? the car wash is open 270 hours a month. (round your intermediate fixed cost values to nearest dollar amount.)