A school cafeteria has the following four activities in serving dinner.

Activity	Time (seconds)
A. Serve drinks and salad	10
B. Serve vegetables	18
C. Serve entree	47
D. Collect payment (last activity)	44

If each activity is performed by a different person, with four employees, what would be the maximum number of customers the cafeteria can serve per hour?

Numbers only, keep three decimals if not exact, either round up or down is ok