Perpetual Inventory Using LIFO Beginning inventory, purchases, and sales for Item ER27 are as follows: July 1 Inventory 98 units @ $31 5 Sale 78 units 11 Purchase 109 units @ $33 21 Sale 92 units Assuming a perpetual inventory system and using the last-in, first-out (LIFO) method, determine (a) the cost of merchandise sold on July 21 and (b) the inventory on July 31. a. Cost of merchandise sold on July 21 b. Inventory on July 31 SA SA