Private Sub Worksheet_Change(ByVal Target As Range)
  If Range("$A$1").Value = "Scanstation P50" Then
    ResetHiddenRows()

    Rows("23:43").EntireRow.Hidden = True
  End If

  If Range("$A$1").Value = "Scanstation P40" Then
    ResetHiddenRows()

    Rows("10:21").EntireRow.Hidden = True
    Rows("35:48").EntireRow.Hidden = True
  End If

  If Range("$A$1").Value = "Scanstation P30" Then
    ResetHiddenRows()

    Rows("10:35").EntireRow.Hidden = True
  End If
End Sub

Private Sub ResetHiddenRows()
  Rows("1:48").EntireRow.Hidden = False
End Sub