I need to divide my total by the QTY, but QTY lives on every row

I hope i explain this correctly
I am dealing with BoMs . . .
If there are 50 rows of parts, for example, on a BoM where the BoM QTY is 6, I need to divide the total of my 50 lines of duty per part by 6.  If the BoM Qty is 60, i need to divid