need solutions with step bty steps

4. {20) A rental car location leases cars to customers. but the cars are returned to another location. It manages eet availability using an s, .S' ituitentorsr system where s = 15 and 5' = 35. That is. if the beginning inventory on a day is less than or equal to s, an order is placed for .S' 3!. Lead time d = 3 days. Replenishment orders are placed at the beginning of the day, and replenishment deliveries are made also at the beginning of the day. \"- a. What is average inventory? b. What is the estimated stocknut probability