The units of an item available for sale during the year were as follows: There are 45 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost under each of the following methods. a. Determine the inventory cost by the first-in, first-out method. $ b. Determine the inventory cost by the last-in, first-out method. $ c. Determine the inventory cost by the average cost method. Do not round intermediate calculation and round final answer to the nearest whole value. $