probably a simple question, but I'm just not figuring this one out....

Column B which is in Spreadsheet B is labeled "Must Ship by Date". We need
it to contain a date which is the shipping date 8 days before the Event Date
in column A from Spreadsheet A.
However, if that Must ship by Date falls on a weekend or holiday (standard)
it needs to ship the previous Friday or previous working day.

I hope that makes sense.

Thanks so much for your help.