\begin{tabular}{ll} Cost of goods sold: & \\ Cost of goods manufactured (2,800 units) & $64,400 \\ Inventory, April 30 (400 units) & (9,200) \\ Total cost of goods sold & (55,200) \\ Gross profit & $21,600 \\ Selling and administrative expenses & (13,600) \\ Operating income & $8,000 \\ \hline \end{tabular} Joplin Company Variable Costing Income Statement For the Month Ended April 30 Sales Variable cost of goods sold: Variable cost of goods manufactured Inventory, April 30 Total variable cost of goods sold Manufacturing margin Variable selling and administrative expenses Contribution margin Fixed costs: Fixed manufacturing costs Fixed selling and administrative expenses Total fixed costs Operating income