Problem A Costner Company uses an absorption costing system in accounting for the single product it manufactures. The following selected data are for the year: Sales (10,000 units) S360,000 Direct materials (variable) $129,600 Direct labor (variable) $43,200 Variable manufacturing overhead $12,960 Fixed manufacturing overhead $17,280 Variable selling and administrative expenses $21,600 Fixed selling and administrative expenses $72,000 . . The company produced 12,000 units and sold 10,000 units. 1. Calculate production cost per unit under variable and absorption costing. 2. Prepare a contribution margin income statement under variable costing. 3. Prepare a multi-step income statement under absorption costing. 4. Explain the reason for the difference in net income between b and c