Product X is made of two units of Y and three of Z. Y is made of one unit of A and two units of B. Z is made of two units of A and four units of C. Lead time for X is one week; Y, two weeks; Z, three weeks; A, two weeks; B, one week; and C, three weeks. a. If 100 units of X are needed in Week 10, develop a planning schedule showing when each item should be ordered and in what quantity. Assume we have no inventory in any of the items to start. b. Repeat (b) using current on-hand inventories of 20 X, 40 Y, 30 Z, 50 A, 100 B, and 900 C.