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4. On September 30, the end of the first month of operations, Bret Company. prepared the following income statement based on absorption costing: Bret Company Absorption Costing Income Statement For Month Ended September 30, 2018 Sales (2,600 units) Cost of goods sold: $117,000 Cost of goods manufactured Less ending inventory (400 units) $85,500 11400 74.100 $42,900 21,500 $21400 Cost of goods sold Gross Profit Selling and administrative expenses Operating income Assume that fixed manufacturing costs were $42,900 and the variable selling and administrative expenses were $14,600. Required: a. How many units were produced in September? b. What is the inventory cost per unit using the absorption costing method? b. What is the inventory cost per unit using the variable costing method? c. Prepare an income statement using variable costing