Modify simple formula to count working days

AI created the following formula to count days remaining for tasks that are not marked as “done”, pretty straightforward. However, when I try and get it to modify the formula to only count “working days” (Mon.-Fri.) it completely fails. How can I tweak this to only count working days? (Side note: I’ve seen other threads that talk about holidays, ect. and that’s not something I’m concerned about in this case).

If([State].[Name] != “Done”, ToDays([Date].End() - Today()), 0)