I tried to do it as calculation in a cell but it gets too cumbersome. But
this code, which I created in about 10 minutes work fine. The only thing you
might want adjusted is that it can end at 5pm the following day if you start
at 5 pm the current day. I don't know about that but test it out. If you
don't know how to set up this as a macro let me know....

Sub CalcIt()
Dim InTime As Double
Dim AddTo As Double
Dim EndMoment As Double
Dim Priority As Integer
Dim TheRow As Double


Let TheRow = ActiveCell.Row

Let InTime = Cells(TheRow, 5) 'E38
Let Priority = Cells(TheRow, 7) 'G38

If Hour(InTime) 17 Then
Let InTime = Int(InTime) + (17 / 24) 'sets to 5pm.
End If



If Priority = 1 Then
Let AddTo = 0.083333
ElseIf Priority = 2 Then
Let AddTo = 0.166666667
ElseIf Priority = 3 Then
Let AddTo = 1
ElseIf Priority = 4 Then
Let AddTo = 2
ElseIf Priority = 5 Then
Let AddTo = 7
End If

Let EndMoment = InTime + AddTo
If Hour(EndMoment) 17 Then 'if end time is after 5 pm then must go to
next day
'Let AddTo = Hour(EndMoment) - 17
Let EndMoment = Int(EndMoment)
Let EndMoment = EndMoment + 1 + (9 / 24) + AddTo 'move to 9 am next day
End If


If Weekday(EndMoment) = 6 Then
Let EndMoment = EndMoment + 2
ElseIf Weekday(EndMoment) = 7 Then
Let EndMoment = EndMoment + 1
End If

Cells(TheRow, 8).Value = EndMoment

End Sub