Reverse date work days calculation

[Mikal]

I currently have a calculation that takes the start date, adds the duration of days and calculates the finish date excluding holidays and weekends. I would like it to do the opposite. Take the finish date, add the duration and back into the start date. excluding Holidays and weeds Any help would be appreciated.

Here is what I have =WORKDAY(G9,F9,nonworking)

Thanks
Mikl

 

[MARK858]

Have you tried...

=WORKDAY(G9,F9*-1,nonworking)

 

[Mikal]

thank you, works great