"Net Credit Sales/Avg Accounts Receivable" gives Debtors Turnover in terms of number of times the receivables balance is sold per year
"Net Sales/Avg Accounts Receivable" gives Average collection period, which is often used to APPROXIMATE Debtor's turnover
365 X 1/(Net Credit Sales/Avg Accounts Receivable) gives Debtors Turnover in terms of average number of days