Please, explain to me how I can solve this.

Concord sells a snowboard, EZslide, that is popular with snowboard enthusiasts. The following is information relating to Concord's beginning inventory and purchases of EZslide snowboards during September. During the same month, 102 EZslide snowboards were sold. Concord uses a periodic inventory system. Compute the ending imventory at September 30 and the cost of goods sold using the FIFO, LIFO, and average-cost methods. (Round per unit cost to 3 decimal places, eg. 15.647 and final answers to 0 decimal places, e.g. 5,125