Como hago esto? ayuda por favor!!

E6-4 Elsa's Boards sells a snowboard. Xest, that is popular with snowboard enthusiasts Information relating to Elsa's purchases of Xarri snowboards during September is shown below. During the same month, 121 Xpea snowboards were sold. Elsa's uses a periodic inventory system Date Explanation Units Unit Cost Sept. 1 Inventory 26 S 97 Sept. 12 Purchases 45 102 Sept. 19 Purchases 20 104 Sept. 26 Purchases SO 105 Instructions (a) Compute the ending inventory at September 30 and cost of goods sold using the FIFO LIFO and AVERAGE methods. Prove the amount allocated to cost of goods sold under cach method