Paul's Manufacturing Has Sales of $810,000

Paul's Manufacturing has sales of $810,000. The cost of goods sold is equal to 80% of sales. The firm has an average inventory of $11,500. How many days on average does it take the firm to sell its inventory?

A) 3.24 days
B) 5.18 days
C) 6.48 days
D) 56.35 days
E) 70.43 days