How do you calculate 15. Thx

Brief Exercise 6-15 At the beginning of the year, Swifty Ltd. had 930 units with a cost of $7 per unit in its beginning inventory. The following inventory transactions occurred during the month of January: Jan. 3 Sold 720 units on account for $13 each. 9 Purchased 960 units on account for $8 per unit. 15 Sold 800 units for cash at $12 each. Your answer is partially correct. Try again. Prepare journal entries assuming that Swifty Ltd. uses FIFO under a perpetual inventory system. (Credit account titles are automatically indented when the amount is entered. Do not indent manually. Record journal entries in the order presented in the problem. If no entry is required, select "No Entry" for the account titles and enter O for the amounts.) Date Account Titles and Explanation Debit Credit Jan. 3 Accounts Receivable 9360 Sales 60 3 Cost of Goods Sold 5040 Inventory 5040 9 Inventory 7680 Accounts Payable 15 Cash 9600 Sales 9600 15 Cost of Goods Sold 2590 Inventory 2590