William Beville's computer training school, in Richmond, stocks workbooks with the following characteristics:

Demand $D=800$ units $/$ year

Ordering cost $S=$$$\frac{25}{?}$ order

Holding cost $H=$$$\frac{4}{?}$ unit $\frac{?}{?}$ year

a$.$ Calculate the EOQ for the workbooks.

b$.$ What are the annual holding costs for the workbooks?

c$.$ What are the annual ordering costs?