The units of an item available for sale during the year were as follows: Jan. 1 Inventory 4 units at $4,200 $16,800 Aug. 7 Purchase 16 units at $4,500 72,000 Dec. 11 Purchase 11 units at $4,700 51,700 31 units $140,500 There are 18 units of the item in the physical inventory at December 31. The periodic inventory system is used. Determine the inventory cost using (a) the first-in, first-out (FIFO) method; (b) the last-in, first-out (LIFO) method; and (c) the weighted average cost method (Round per unit cos