Engine Central had the following sales transactions in December: Dec. 4 7 Sold $9,800 of merchandise on account to Mo's Motors, terms 4/15, net 30. Cost $4,900. Mo returned $1,800 of merchandise to Engine Central because he changed his mind and wanted to order a different type of engine. Cost $900. 16 Mo paid the balance owing to Engine Central. Prepare the journal entries to record the sales transactions on the books of Engine Central using a perpetual inventory system and the earnings approach for revenue recognition. (Credit account titles are automatically indented when the amount is entered. Do not indent manually. If no entry is required, select "No Entry" for the account titles and enter O for the amounts.)