computed field in view

Hi guys,

I have created a view in AOT which has data source query (static AOT Query)

i have calculated sum of purchline amount that is correct and it gives correct result,

but somebody guide me how i will calculate multiplication of two fields in AOT View like Tsql (Sum(pl.LINEAMOUNT)*sum(pl.PURCHQTY)))

and subtraction of ,(sum(pl.PURCHQTY)-sum(vpst.QTY))'Balance Receipt Qty'