Perpetual Inventory Using LIFO Beginning inventory, purchases, and sales for Item PK95 are as follows: October 1 Inventory 80 units @ $31 5 Sale 64 units 11 Purchase 89 units @ $33 21 Sale 75 units Assuming a perpetual inventory system and using the last-in, first-out (LIFO) method, determine (a) the cost of merchandise sold on October 21 and (b) the inventory on October 31. a. Cost of merchandise sold on October 21 b. Inventory on October 31