The financial statements of the Darlington Company report net sales of $500,000 and accounts receivable of $40,000 and $20,000 at the beginning of the year and end of year, respectively. What is the accounts receivable turnover for Darlington?

I learned that "Accounts receivable turnover is Net Credit Sales/Average Net Accounts Receivable." So I thought 500,000/ (40,000+20,000) = 8.33..

But the answer says 16.7 is correct. Can you explain how to get answers from the question above?