I work with a schedule that is based on weeks in a year, for example, 0605.
This would be the sixth week of 2005. I need to schedule backwards based on
an end date 0406.
I know the end date, 4505 or 0406 (may be in cell D1 and D2).
I know the duration, for example 10 weeks and 12 weeks (may be in cell C1
and C2).
What I am looking for help is a formula for how to find a start date.

Cell D1 = 4505
Cell C1 = 10
Cell B1 = 3505 (what is the formula to get this).

Cell D2 = 0406
Cell C2 = 12
Cell B2 = 4405 (what is the formula to get this).

I deal with about 100 to 150 of these in each spreadsheet.

I am using MS Excel 97