I have the following formula:
=SUMIF('weekly dates'!A1:AZ1,""&A5,Details!L7:BK7)

Weekly dates is a static sheet, &A5 is the current date and Details!L7:BK7
are cells that are calculated weekly on a sheet different from where this
formula is used.

There are 4 weeks per period and this report is done weekly. I need the
SUMIF to be just as it is for week 1, but for week 2, I need to include weeks
1&2, week 3 to include 1-3 and week 4 to include 1-4. Then it starts over
after week 4. I can do by changing the formula weekly in the following way.
=SUMIF('weekly dates'!A1:AZ1,""&A5-8,Details!L7:BK7) week2
=SUMIF('weekly dates'!A1:AZ1,""&A5-16,Details!L7:BK7) week3
=SUMIF('weekly dates'!A1:AZ1,""&A5-24,Details!L7:BK7) week4

I know there has to be a cleaner and more correct way of doing this. Any
ideas?