The Lakeshore Hotel's guest-days of occupancy and custodial supplies expense over the last seven months were: Guest-days is a measure of the overall activity at the hotel. For example, a guest who stays at the hotel for three days is counted as three guest-days. Required: 1. Using the high-low method, estimate a cost formula for custodial supplies expense. (Round the variable cost per guest-day to 2 decimal points.)