Need help in C and D only. Thanks

7.22 Consider three items with the following profiles: a. What is the total demand in cube for items A, B, and C? b. If 20ft3 of space is allocated for item C, how many times will the item be replenished in one year? c. If each item is to receive a location in the forward area and an equal-time-supply allocation policy is used, how much space will be allocated for each item assuring a one-week time supply (assume 50 weeks)? d. If the items are to be assigned locations in the forward area on the basis of popularity storage, and they are allocated space as in part c, rank the items so as to maximize the number of picks in the most accessible storage space