问题如下：
Given the following financial statement data, calculate the operating cycle for this company.
The operating cycle for this company is closest to:
选项：
A. 42.0 days.
B. 47.9 days.
C. 78.5 days.
解释：
C is correct.
Number of days of inventory = $2,300/($20,000/365) = 41.975 days（大家注意此处答案用的是ending数据，但应该使用average inventory)
Number of days of receivables = $2,500/($25,000/365) = 36.5 days
Operating cycle = 41.975 + 36.5 days = 78.475 days
Note: The net operating cycle is 47.9 days.
Purchases = $20,000 + $2,300 − $2,000 = $20,300
Number of days of payables = $1,700/($20,300/365) = 30.567 days
The net operating cycle is 78.475 − 30.567 = 47.908 days
有两个问题没弄懂，1.能不能从概念上帮我区分下credit sales和accounts receivables 2.题目求的是operating cycle，不是net operating cycle，为什么还要减days of payable？
