On August 31, Pharoah Supply had an inventory of 20 backpacks at a cost of $18 each. The company uses a perpetual inventory system. During September, the following transactions and events occurred: Sep. 3 Purchased 66 backpacks at $25 each from Janzen, terms n/30. Received a 10% quantity discount. 6 Received credit of $90 for the return of four backpacks purchased on September 3 that were defective. 7 Paid for the September 3 purchase. 9 Sold 20 backpacks for $35 each to McGill Books, terms n/30. The cost of each backpack was $18 each. 13 Cash sales of 15 backpacks for $35 each to Calvin Office Supply. 21 Purchased 27 backpacks at $18 each from Coleman Company, terms 2/10, n/30. 30 A physical inventory count indicated an ending inventory balance of $830.