Inventory Costing Methods-Perpetual Method Chen Sales Corporation uses the perpetual inventory system. On January 1, 2015, Chen had 1,000 units of product A with a unit cost of $20 per unit. A summary of purchases and sales during 2015 follows: Required Assume that Chen uses the first-in, first-out method. Compute the cost of goods sold for 2015 and the ending inventory balance at December 31, 2015, for product A. Assume that Chen uses the last-in, first-out method. Compute the cost of goods sold for 2015 and the ending inventory balance at December 31, 2015, for product A. Assume that Chen uses the weighted-average cost method. Compute the cost of goods sold for 2015 and the ending inventory balance at December 31, 2015, for product A. Do not round until your final answers. Round to the nearest dollar