On October 20, Cullumber sells merchandise at a cost of $3,840 to Blossom for $6,400 cash. On October 25, Cullumber received returned goods from Blossom and refunds the amount in cash for items that had a selling price of $640 and a cost of $384. Use a tabular summary to record the transactions for Cullumber Company using a perpetual inventory system. Include margin explanations for the changes in revenues and expenses.