What did I do wrong?

Chart of Accounts Journal ournalize entries for the following related transactions of South Coast Heating & Air Company. Refer to the Chart of Accounts for exact wording of account titles. Mar. Purchased$48,000 of merchandise from Atlas Co. on account, terms 1/10, n/30. 1 9 Paid the amount owed on the invoice within the discount period Discovered that $7,500 of the merchandise purchases on Mar. I was defective and returned items, receiving credit. 11 18 Purchased $6,000 of merchandise from Atlas Co, on account, terms n/30 20 Received a refund from Atlas Co. for return on Mar. 11 less the purchase on Mar. 18