Wind Productions uses flexible budgets. Items from the budget for March in which 3,000 units were produced and sold appear below: Direct materials $18,000 Indirect materials variable 2,000 Supervisor salaries 15,000 Depreciation on factory equipment 4,000 Direct labor 10,000 Property taxes on factory 1,000 Instructions If Wind prepares a flexible budget at 4,000 units, compute its total variable cost