The following data refer to one year for Monroe Fabricators. Fill in the blanks. Direct materials inventory, January 1 $ 2,770 Direct materials inventory, December 31 Work-in-process inventory, January 1 2,900 Work-in-process inventory, December 31 Finished goods inventory, January 1 3,780 1,720 Finished goods inventory, December 31 320 Purchases of direct materials 16,060 Cost of goods manufactured during the year 53,880 Total manufacturing costs Cost of goods sold 55,280 Gross margin 48,010 Direct labor Direct materials used 14,530 Manufacturing overhead 13,800 Sales revenue