The Sandy Bay is a trader in sand. On December 31, 2010 the closing inventory was completely destroyed by flood rains. The following information is available: (1) Inventory at December 1, 2010 at cost $31,400 (2) Purchases for December 2010 $55,600 (3) Sales for December 2010 $88,800 (4) Standard mark-up is 25% Based on this information, what was the value of the closing inventory? a. $15,960 b. $17,760 c. $20,400 d. $25,800