A proprietor of a restaurant knows that will need 40, 70, and 60 tablecloths on Thursday, Friday, and Saturday respectively for scheduled banquets. He can rent tablecloths for 3 days for $2 each. A tablecloth must be laundered before it can be reused. He can have them cleaned overnight for $1.50 each. He can have them laundered by regular one day service (e.g. one used on Thursday can be reused on Saturday) for $0.80 each. There are currently 20 clean tablecloths on hand with none dirty or at the laundry. Rented tablecloths need not be cleaned before returning. 

a) Formulate the problem as a transportation problem to minimize the total costs of renting and laundering the tablecloths. 

b) What is the total cost for 3 days' napkin usage and laundering?