Please explain how to get to the Answer A. Thank you

Co. uses the retail inventory method to estimate its inventory for interim statement purposes. Data relating to the computation of the inventory at July 31, 2014, are as follows: Under the retail inventory method (regular method used to approximate average cost assumption, not the conventional retail method), Henke's estimated inventory at July 31, 2014 is: $171,423. $186,000. $162,000. $173,259