Perpetual Inventory Using LIFO Beginning inventory, purchases, and sales data for prepaid cell phones for May are as follows: Inventory May 1 Purchases May 10 May 20 2,100 units at $37 May 12 May 14 May 31 1,470 units 1,260 units 630 units 1,050 units at $39 945 units at $41 a. Assuming that the perpetual inventory system is used, costing by the LIFO method, determine the cost of merchandise 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 Merchandise Sold Unit Cost column and LOWER unit cost first in the Inventory Unit Cost column