Periodic System-Computing Cost of Sales and Gross Profit under FIFO and LIFO physical inventory taken on March 31 showed 130 units available in inventory. Valley uses the periodic inventory system. a. Compute cost of goods sold and ending inventory for the first quarter of the year using (1) FIFO and (2) LIFO. - Note: Do not use any negative signs with your answers. c. Prepare a schedule showing the gross profit and gross profit percentage for each method in part a assuming all units sold during the quarter were at a price of $300 each. - Note: Do not use any negative signs with your answers