Periodic Inventory by Three Methods The units of an item available for sale during the year were as follows: Jan. 1 Inventory 12 units at $25 Feb. 17 Purchase 7 units at $26 Jul. 21 Purchase units at $27 Nov. 23 Purchase 5 units at $20 There are 6 units of the item in the physical inventory at December 31. The periodic inventory system is used. Round average unit cost to the nearest cent and final answers to the nearest whole dollar, if required. a. Determine the Inventory cost by the first in, first-out method. b. Determine the Inventory cost by the last in, first-out method.