EXCEL VBA HORIZONTAL ADDITION/LOOP

Sub FixMe()
Dim Cell As Range
Dim lMaxRows As Long
Dim iMaxCols As Integer

    ' this is used to located the last row on the sheet
    Set Cell = Cells.Find("*", Cells(1, "A"), SearchOrder:=xlByRows, SearchDirection:=xlPrevious)
    
    If Cell Is Nothing Then
       lMaxRows = 0
    
    Else
       lMaxRows = Cell.Row
    End If
    
    
    ' this is used to located the last used column on the sheet
    Set Cell = Cells.Find("*", Cells(1, "A"), SearchOrder:=xlByColumns, SearchDirection:=xlPrevious)
    
    If Cell Is Nothing Then
       iMaxCols = 0
    
    Else
       iMaxCols = Cell.Column
    End If
    
    
    Set Cell = Nothing ' to destroy and free memory
    
    ' if the number of rows on the sheet is less than 5 then exit the routine
    If lMaxRows < 5 Then Exit Sub
    
    ' for each row starting from row 5 till last row of the sheet.
    With Range(Cells(5, "J"), Cells(lMaxRows, "J"))
    
         ' putting formula in J column as Sum(AC, AD). In formula RC29,
         ' R means same row where the formula is being written
         ' C29, means that 29th column of sheet (column AC)
        .FormulaR1C1 = "=SUM(RC29, RC30)"
        
        ' copying the column J
        .Copy
        
        ' pasting the values back on J as values to get rid of formula
        .PasteSpecial xlPasteValues
    
    End With
    
    'clearing every thing from column M till last column
    Range(Cells(5, "M"), Cells(lMaxRows, iMaxCols)).Clear
    
End Sub