Periodic method of inventory costs. Please be descriptive on how to find the answers.

Inventory Costing Methods-Periodic Method The Gleem Sales Corporation uses the periodic inventory system. Or January 1. 2012, Gleem had: 2.600 units of product B with a unit cost of $80 per unit. A summary of purchases and sales during 2012 follows Fin UnitUnits Units Cost Purchased Sold Jan.3 Mar.8 $84 3,000 June 13 Sept.19 90 Nov.23951,200 Dec.28 1,600 2,000 800 1,800 Required a. Assume that Gleem uses the first-in, first-out method. Compute the cost of goods sold for 2012 and the ending b. Assume that Gleem uses the last-in, first-out method. Compute the cost of goods sold for 2012 and the ending c Assume that Gleem uses the weighted-average cost method. Compute the cost of goods sold for 2012 and the ending inventory balance at December 31, 2012, for product B inventory balance at December 31, 2012, for product B. inventory balance at December 31. 2012, for product B