Perpetual inveritory using riro The following units of a particular item were avalabie for sale during the calendar year: The firm maintains a perpetual imventory system. Determane the cost of goods sold for each sale and the inventury balance after each sale, assurnirg the first-in, first-aut method. Present the data in the form illustrated in Exhibic 3. Under Fro, if units are in inventory at two different costs, enter the units with the LOWER urst cost first in the Cont of Goods Sold Unit Cost column and in the Inventory Unit Cost column