Hello, can you please explain the work. I'm confused about how to find the fourth unit number to find cogs. I need help with the whole problem.

Sharon's Boards sells a snowboard, Xpert, that is popular with snowboard enthusiasts. Information relating to Sharon's purchases of Xpert snowboards during September is shown below. During the same month, 118 Xpert snowboards were sold. Sharon's uses a periodic inventory system. Date Explanation Units Unit Cost Total Cost Sept. 1 Inventory 26 $97 $2,522 Sept. 12 Purchases 45 105 4,725 Sept. 19 Purchases 20 107 2.140 Sept. 26 Purchases 50 108 5.400 Totals 141 $14,787 (a) * Your answer is incorrect. Compute the ending inventory at September 30 and cost of goods sold using the FIFO and LIFO methods FIFO LIFO The ending inventory at September 30 $ 2,160 $ 1.940 Cost of goods sold $ 12,267 $ 12847 2522 4725 240 340 1 EI: 141-118-23 COGS: 66.97) +(45.105)-[20.07(30.109) = 12,622 1 @ Sept 26:23:10% -2,484 COGS (50-108)+(20:107)=(18-105) 24.92) =