OB). 3 PE 7-3A Perpetual inventory using LIFO Beginning inventory, purchases, and sales for Item Zebra 9x are as follows: April Inventory 420 units at $8 10 Sale 300 units 18 Purchase 280 units at $9 27 Sale 250 units Assuming a perpetual inventory system and using the last-in, first-out (LIFO) method, deter- mine (a) the cost of merchandise sold on April 27 and (b) the inventory on April 30