marco can build a lap top twice as fast as cliff. working together, it takes them 5 hours. how long would it have taken marco working alone?

Little's law can be applied to any part of the store, such as a particular department or the checkout lines. the store owner determines that, during business hours, approximately 84 shoppers per hour make a purchase and each of these shoppers spend an average of 5 minutes in the checkout line. at any time during business hours, about how many shoppers, on average, are waiting in the checkout line to make a purchase at the good deals store?