Calculation at row level and summing at front end

[qlik4asif]

Hello Guys,

I need your help for the below requirement.

In Back end i have 2 tables as below

I need the sum of Sales (QTY * Unit Price) in a KPI.

The Sum Value is 445 for above example.

I know we can do it at back end by combining both tables and creating a new column with QTY*Unit Price.

For some reason i can't do it in back end,

is it possible to achieve in front end.

Thanks in Advance