. The required maintenance workload for the next four months is 400, 600, 300 and 500 man-hours, respectively. The demand can be met by either regular time at a cost of 13 birr per hour or overtime at a cost of 20 birr per hour. Regular time and overtime capacities are respectively 400 and 100 h per month. Early maintenance costs 3 birr per hour per month, while late maintenance costs 5 birr per hour per month. Using the modified transportation method, develop the capacity plan to satisfy the required workload.