World Airlines has three service deportments: (1) ticketing, (2) baggage handling, and (3) engine maintenance. The service department costs are estimated for separate cost pools formed by department and are allocated to two revenue-producing departments: (1) domestic flights and (2) international flights. World does not differentiate between fixed and variable costs in making allocations. The following data relate to the allocations: Allocate the service department costs to the revenue-producing departments using air miles as the allocation base