Kathy is a repair technician for a phone company. Each week, she receives a batch of phones that need repairs. The number of phones that she has left to fix at the end of each day can be estimated with the equation P=108−23d P = 108 − 23 d , where P is the number of phones left and d is the number of days she has worked that week. What is the meaning of the value 108 in this equation?