The accounting records of Shamrock Electronics show the following data Beginning inventory 2.700 units at $7 Purchases 6,300 units at $9 Sales 7,570 units at $12 Determine cost of goods sold during the period under a periodic inventory system using (a) the FIFO method. (b) the LIFO method, and (c) the average cost method. FIFO LIFO Average-cost $ $ $ Cost of goods sold