please explain

Ivanhoe Company sells a snowboard, EZslide, that is popular with snowboard enthusiasts. Below is information relating to Ivanhoe Company's purchases of EZslide snowboards during September. During the same month, 105 EZslide snowboards were sold Date Sept. 1 Sept. 12 Sept. 19 Sept. 26 Explanation Units Unit Cost Total Cost Inventory Purchases Purchases Purchases Totals 13 47 51 20 131 $94 97 98 $1,222 4,559 4,998 1,980 $12,759 Additional data regarding the company's sales of EZslide snowboards are provided below. Assume that Ivanhoe Company uses a perpetual inventory system Date Sept. 5 Sept. 16 Sept. 29 Units Sale Sale Sale 8 50 47 105 Totals Calculate the average unit cost. (Round answers to 3 decimal places, e.g. 5.125.) September1 s September5 s September 12 s September 16 s September 19 s September 26 s September 29 s