The units of Manganese Plus available for sale during the year were as follows: Mar. 1 Inventory 21 units @ $29 $609 June 16 Purchase 31 units @ $32 992 Nov. 28 Purchase 45 units @ $36 1,620 97 units $3,221 There are 10 units of the product in the physical inventory at November 30. The periodic inventory system is used. Round answers to the nearest whole dollar. a. Determine the inventory cost by the FIFO method. $ b. Determine the inventory cost by the LIFO method. c. Determine the inventory cost by the average cost methods. $