example: imagine a month has 22 billing days and the current billing day is 10. Then remaining billing days is 12. I want to calculate the average sales for the last 3 months when 12 billing days are remaining. The last 3 months excludes the current month. So if the current month is July 2018 then i need the average sales of June,May and April with 12 billing days remaining in each of these months. I want this to be dynamic which updates on a daily basis. Please help.