Joe is a repair technician for a computer company. Each week he has a batch of computers that needs fixed. The number of computers that he has left to fix at the end of each day can be estimated with the equation C = 18 - 7d , where C is the number of computers left and d is the number of days he has worked that week. What is the meaning of the value 18 in this equation?

a. Joe will complete the repairs within 18 days

b. Joe starts each week with 18 computer to fix

c. Joe repairs computers at a rate of 108 per day

d. Joe receives 18 new computers each day that need fixed.