Product $A$ is an end item and is made from two units of $B$ and four of $C.B$ is made of two units of $D$ and two of $E.C$ is made of two 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 $120$ 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. $($Leave no cells blank $-$ be certain to enter $"0"$ wherever required.$)$