a$.$ If A has a gross requirement to build $250$ units and an on$-$hand inventory for $A$ of $40,$ determine the

net requirement for $D$ if its current on$-$hand inventory balance for $D$ is $20($all other components

have no current inventory$).$

b$.$ Determine the net requirement for $F$ if the gross requirement for $A$ is still $250$ and current on$-$hand

inventory balance for $A$ is $40,D$ is $20,$ and $F$ is $60.$