Sandhill Corporation manufactures a single product. Monthly production costs incurred in the manufacturing process are shown below for the production of 3,900 units. The utilities and maintenance costs are mixed costs. The fixed portions of these costs are $387 and $258, respectively. Production in Units 3,900 Production Costs Direct materials $9.675 Direct labor 27,420 Utilities 3,702 Property taxes 1.290 Indirect labor 5.805 Supervisory salaries 2,451 Maintenance 1,233 Depreciation 3,096 Identify the above costs as variable, fixed, or mixed. Costs Direct materials Direct labor Utilities Property taxes Indirect labor Supervisory salaries