Obtain Last Working Date before Current Row Date

Assuming Working Days are from Monday to Friday, we want the following

First Add a custom Column to identify day of the week as follows

=Date.DayOfWeek([Dateslist],1)+1

Now we can get last working day using this custom column

=let mydate=[Dateslist] in

List.Max(
Table.SelectRows(AddedCustom,each [Dateslist] < mydate and [DayofWeek] <6)[Dateslist]
         )