The units of Manganese Plus available for sale during the year were as follows: There are 18 units of the product in the physical inventory at November 30 . The periodic inventory system is used. 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 weighted average cost methods. Round intermediate calculations and final answer to two decimal places. $