Beginning inventory, purchases, and sales for an inventory item are as follows: Sep. 1 Beginning Inventory 31 units $13 5 Sale 18 units 17 Purchase 32 units $14 30 Sale 34 units Assuming a perpetual inventory system and the first-in, first-out method, determine (a) the cost of the goods sold for the September 30 sale and (b) the inventory on September 30. a. Cost of goods sold $ b. Inventory, September 30