If variable manufacturing costs are $9 per unit and total fixed manufacturing costs are $435,000, what is the manufacturing cost per unit if: a. 5,800 units are manufactured and the company uses the variable costing concept? $ b. 7,500 units are manufactured and the company uses the variable costing concept? $ c. 5,800 units are manufactured and the company uses the absorption costing concept? $ d. 7,500 units are manufactured and the company uses the absorption costing concept