US Airways is one of the nation's leading commercial air carriers, with hubs Phoenix and l, as Vegas. Here are some the costs incurred by US Airways (1. Airplane fuel, 2. Flight attendants' salaries, 3. Baggage handlers' salaries, 4. In-flight meals, 5. Pilots' salaries, 6. Airplane depreciation and 7. Advertising), For each cost, list the appropriate cost driver; Indicate whether the cost is likely to he fixed, variable, or mixed in relation to your cost driver