Family Furniture Corporation incurred the following costs. Identify the costs as variable, fixed, or mixed. 1. Wood used in the production of furniture. 2. Fuel used in delivery trucks. 3. Straight-line depreciation on factory building. 4. Screws used in the production of furniture. 5. Sales staff salaries. 6. Sales commissions. 7. Property taxes. 8. Insurance on buildings. 9. Hourly wages of furniture craftsmen. 10. Salaries of factory supervisors. 11. Utilities expense. 12. Telephone bill