S
If(WeekDayName(Dates.Start(),"dy") = "mon",0,If(WeekDayName(Dates.Start(),"dy") = "tue",1,If(WeekDayName(Dates.Start(),"dy") = "wed",2,If(WeekDayName(Dates.Start(),"dy") = "thu",3,If(WeekDayName(Dates.Start(),"dy") = "fri",4,If(WeekDayName(Dates.Start(),"dy") = "sat",5,6))))))
E
If(WeekDayName(Dates.End(),"dy") = "mon",6,If(WeekDayName(Dates.End(),"dy") = "tue",5,If(WeekDayName(Dates.End(),"dy") = "wed",4,If(WeekDayName(Dates.End(),"dy") = "thu",3,If(WeekDayName(Dates.End(),"dy") = "fri",2,If(WeekDayName(Dates.End(),"dy") = "sat",1,0))))))
Weekdays
(((((ToDays(Dates.End(false) - Dates.Start()) + S) + E) * 5) / 7) - If(S > 5,5,S)) - If(E < 3,0,E - 2)