how to adjust this line of vba

[storemannequin]

I'm trying to replace the hard-coded in "AW" column with a variable for the final column but can't figure out how to situate it in this line of code, also in the formula. I want to sum the content of the last column from the first cell to the very last:

Range("AW" & TotalRw).Formula = "=SUM(AW2:AW" & TotalRw - 1 & ")"

 

[wigi]

LastCol = Cells(TotalRw, Columns.Count).End(xlToLeft).Column
Cells(TotalRw, LastCol).Formula = "=SUM(R2C:R[-1]C)"