Perpetual Inventory Using FIFO Beginning inventory, purchases, and sales data for prepaid cell phones for May are as follows: Inventory Purchases Sales May 1 2,400 units at $36 May 10 1,200 units at $38 May 12 1,680 units 20 1,080 units at $40 14 1,440 units 31 720 units Assume that the business maintains a perpetual inventory system, costing by the first-in, first-out 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 3. Under FIFO, if units are in inventory at two different costs, enter the units with the LOWER unit cost first in the Cost of Merchandise Sold Unit Cost column and in the Inventory Unit Cost column.