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. Draw the bill of materials (product structure tree).

b. 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.