Marshall Cabinet Manufacturing uses flexible budgets that are based on the following manufacturing data for the month of July: Direct materials $8 per unit Direct labor $5 per unit Electric power (variable) $0.30 per unit Electric power (fixed) $4,000 per month Supervisor salaries $15,000 per month Property taxes on factory $4,000 per month Straight-line depreciation $2,900 per month Prepare a flexible budget for Marshall, based on production of 10,000, 15,000,and 20,000 units