Beginning inventory, purchases, and sales for an inventory item are as follows: Sep. 1 Beginning Inventory 30 units @ $20 5 Sale 17 units 17 Purchase 31 units @ $21 30 Sale 32 units Assuming a perpetual inventory system and the first-in, first-out method: a. Determine the cost of the goods sold for the September 30 sale. b. Determine the inventory on September 30