The following data refer to one year for Monroe Fabricators. Fill in the blanks. Direct materials inventory, January 1 $ 2,420 Direct materials inventory, December 31 Work-in-process inventory, January 1 2,730 Work-in-process inventory, December 31 3,790 Finished goods inventory, January 1 1,990 Finished goods inventory, December 31 350 Purchases of direct materials 16,110 Cost of goods manufactured during the year 53,630 Total manufacturing costs Cost of goods sold 55,270 Gross margin 48,190 Direct labor Direct materials used 14,480 Manufacturing overhead 13,620 Sales revenue