Garrison Company uses the retail method of inventory costing. It started the year with an inventory that had a retail cost of $46,200. During the year, Garrison purchased an inventory with a retail sales value of $734,300. After performing a physical inventory, Garrison calculated the inventory cost at retail to be $57,200. The mark up is 100% of cost. Determine the ending inventory at its estimated cost.

a.$143,000

b.$57,200

c.$28,600

d.$85,800