3. The Lessman Furniture Company has the following information available regarding costs at various levels of monthly production: 10 points Production volume (units) 8,000 Units 11,000 Units Direct materials $35,000 $50,000 Direct labor 33,000 45,000 Indirect materials 10,500 15,000 Supervisors' salaries 6,000 6,000 Depreciation on plant and equipment 5,000 5,000 Maintenance 16,000 22,000 Utilities 7,500 10,500 Insurance on plant and equipment 800 800 Property taxes on plant and equipment 1.000 1,000 Total $114,800 $155,300 Develop an equation for total monthly production costs using the high-low method of cost estimation, and predict total costs for a monthly production volume of 18,000 units