Keaton Accessories uses a perpetual inventory system. The company's beginning inventory of a particular product and its purchases during the month of January were as follows: on January 24, Keaton sold 100 units of this product. The other 80 units remain in inventory at January 31. a. Determine the cost of goods sold using each of the following flow assumptions: b. Determine the cost of the 80 units in inventory at January 31 using each of the following flow assumptions