The units of Product B available for sale during the year were as follows: May 1 Inventory 67 units $42 July 30 Purchase 51 units $46 Dec. 31 Purchase 45 units $48 There are 82 units of the product in the physical inventory on December 31. The periodic inventory system is used. Determine the cost of goods sold by (a) FIFO, (b) LIFO, and (c) average cost methods