Garrison Company uses the retail method of inventory costing. It started the year with an inventory that had a retail cost of $49,700. During the year, Garrison purchased an inventory with a retail sales value of $670,100. After performing a physical inventory, Garrison calculated the inventory cost at retail to be $72,800. The mark up is 100% of cost. Determine the ending inventory at its estimated cost. a. $72,800 b. $36,400 c. $109,200 d. $182,000.