On the basis of the following data, what is the estimated cost of the inventory on May 31 using the retail method?

		Cost		Retail
May 1	Inventory	$23,120		$38,530
May 1-31	Purchases	37,350		79,580
May 1-31	Sales			92,150

Do not round intermediate calculations. Round your final answer to the nearest whole dollar.

a. $31,680

b. $8,630

c. $21,921

d. $13,291