90 days after May 30, will be August 28 on a 2010 calendar.
August 28, 2012
Adding 120 days to August 30 gives December 28.
August 28, 2012
Thursday, July 28, 2011
Subtracting 246 days from April 2 2011 gives July 30, 2010.
5 days of a date is a deadline so let's use today's date April 24, 2012. 5 days within April 24, 2012 will be April 29, 2012 which falls on a Sunday. However, within 5 business days of April 24, 2012 is May 1, 2012
Assuming for simplicity that January 1st falls on Monday, and the year is 365 days long, Week 30 would be Monday 23rd July.
It means 30 days after the date the invoice is received.
120 days before Monday, August 30, 2010 = Sunday, May 2, 2010.
May 30th in regular years; May 29th in leap years
There are 31 days in May, 30 in June and 31 in July. 180 days after May 9, 2011 is August 7, 2011.
3,654 days from the start date to the end date, end date included.