Additional information: Subcontracting: 100 units available over the 5 -month period, Beginning inventory: 0 units Costs: Regular time cost per unit =$100 Overtime cost per unit =$125 Subcontract cost per unit =$135 Inventory holding cost per unit =$3. Assume that back-orders are not permitted. a. Using the transportation method, what is the total cost of the optimal plan? b. Does any regular time production go unused? If soot, how much is used or not used? c. What is the total cost of the plan if ending inventory required for the next planning period is: 20 units (include holding costs in the overall calculation)