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