Beginning inventory, purchases, and sales data for prepaid cell phones for December are as follows: Inventory Purchases Sales Dec. 1 3,000 units at $28 Dec. 10 1,500 units at $30 Dec. 12 2,100 units Dec. 20 1,350 units at $32 Dec. 14 1,800 units Dec. 31 900 units a. Assuming that the perpetual inventory system is used, costing by the LIFO method, determine the cost of goods sold for each sale and the inventory balance after each sale, presenting the data in the form illustrated in Exhibit 4. Under LIFO, if units are in inventory at two different costs, enter the units with the HIGHER unit cost first in the Cost of Goods Sold Unit Cost column and LOWER unit cost first in the Inventory Unit Cost column. Schedule of Cost of Goods Sold LIFO Method Prepaid Cell Phones Cost of Cost of Quantity Purchases Purchases Quantity Goods Sold Goods Sold Inventory Inventory Inventory Date Purchased Unit Cost Total Cost Sold Unit Cost Total Cost Quantity Unit Cost Total Cost Dec. 1 3,000 28 84,000 Dec. 10 1,500 30 45,000 3,000 V 28 V 84,000 1,500 V 30 V 45,000 Dec. 12 1,500 30 45,000 28 V Dec. 14 Dec. 20 1,350 X X Dec. 31 900 X X 0000 Dec. 31 Balances