pls answer a b c and d.

3. We deal with computer memory chips. D'N(500, 20^2) boxes monthly. Delivery lead time is 4 days. When we order, the mailing cost of the order is $30, and delivery cost is $200 each time, which is independent of the order quantity. Yearly holding cost of each box is $10/box/year. The shortage cost, which is not dependent on the length of shortage, is $17/unit. Use the approximation discussed in class. Use the time unit of week. Shortage orders are backlogged. (1 week = 5 days, 1 month = 4 week, 1 year = 48 weeks) (a) Determine the order quantity. (b) Determine the reorder point. (c) Determine the safety stock. (d) If we increase the reorder point by two units, how much does the inventory holding cost increases per year? Use the assumption of (r.) policy for the derivation of r and a formulas