Cells(i + 19, 7) = Application.WorksheetFunction.Sum(Cells(i + 7, 5).Value, Cells(i + 8, 5).Value, Cells(i + 9, 5).Value, Cells(i + 10, 5).Value, Cells(i + 11, 5).Value, Cells(i + 12, 5).Value, Cells(i + 13, 5).Value, Cells(i + 14, 5).Value, Cells(i + 15, 5).Value, Cells(i + 16, 5).Value, Cells(i + 17, 5).Value, Cells(i + 18, 5).Value, Cells(i + 19, 5).Value) / 13