Product A is an end item and is made from three units of B and four of C. B is made of three units of D and two of E. C is made of three units of F and two of E. A has a lead time of one week. B, C, and E have lead times of two weeks, and D and F have lead times of three weeks. b. If 90 units of A are required in Week 10, develop the MRP planning schedule, specifying when items are to be ordered and received. There are currently no units of inventory on hand. Note: Leave the cells blank, whenever zero (0) is required