A simulation is to be conducted for a simplified version of the No Thai! Restaurant. Customers first go to a front desk to place their orders and pay. Then they move to a waiting area to wait for their food. Once the food is ready they pick it up and leave the restaurant immediately. The front desk can only serve one customer at a time, and people have to wait in line if the front desk is busy. If we are interested in the average time customers spend in the restaurant, what are the necessary events, activities, entities, locations, and state variables in this system?