Please help with the wrong answer

Return to question ! Required information Use the following information for the Quick Study below. Trey Monson starts a merchandising business on December 1 and enters into the following three inventory purchases. Also, on December 15, Monson sells 30 units for $25 each. Purchases on December 7 Purchases on December 14 Purchases on December 21 20 units @ $10.00 cost 36 units @ $15.00 cost 30 units @ $18.00 cost QS 5-11 Perpetual: Inventory costing with LIFO LO P1 Required: Monson sells 30 units for $25 each on December 15. Monson uses a perpetual inventory system. Determine the costs assigned to the December 31 ending inventory when costs are assigned based on LIFO. Answer is complete but not entirely correct. Perpetual LIFO: Cost of Goods Sold Inventory Balance Goods purchased Cost Cost of Goods per Available for unit Sale # of units Date # of units sold Cost per unit Cost of Goods Sold # of units Cost per unit Inventory Balance 20 la 20 $ 200.00 @ $ 200.00 10.00 10.00 December 7 December 14 36 @ $ 540.00 36 @ $360.00 15.00 $ 10.00 $ 15.00 20 300.00 $ 660.00 December 15 30 @ $ 15.00 $ 450.00 6 X @ 20 X @ $ 15.00 = $ 90.00 $ 200.00 10.00 $ 290.00 December 21 30 $ 540.00 18.00 30 @ $ 540.00 6 @ $ 90.00 18.00 $ 15.00 $ 10.00 20 X @ = $ 200.00 Totals $ 450.00 $ 830.00