Locker Rentals Corp. (LRC) operates locker rental services at several locations throughout the city, including the airport, bus depot, shopping malls, and athletics facilities. Unlike some of the old mechanical lockers that charge a fixed amount per use, LRCs lockers operate electronically and are able to charge based on hours of use. The locker system transmits a daily message to LRCs office indicating the number of hours that lockers have been used. The office manager uses this to determine when cash should be picked up at each location. LRCs cash receipts system is described below. Two employees (cash collection clerks) are responsible for collecting cash from the lockers. Based on instructions from the office manager, one clerk collects cash