Donald Company prepared the following full-absorption-costing income statement for the year ended May 31, 2013: Sales (16,000 units) $320,000 Cost of goods sold 216,000 Gross margin $104,000 Selling and administrative expenses 46,000 Operating income $58,000 Additional information follows: 17,500 units are produced. Selling and administrative expenses include $1.50 of variable cost per unit sold. Variable manufacturing costs were $11 per unit. Required: Prepare a variable-costing income statement for the same period