4. a. Given the following forecast and steady regular output of 550 every month, what total cost would result if owertime is limited to a maximum of 40 units a month, and subcontracting is limited to a maximum of 10 units a month? Unit costs are: Regular output =$20 Overtime $30 Subcontract =$25 Average Inventory =$10 Backlog =$18 b. Suppose now that backlogs are not allowed. Modify your plan from-part a to accommodate that new condition as economically as possible. The limits on overtime and subcontracting remain the same