Computing And Assigning A Value To A Textbox From Other Data Regions

I am new to SSRS, so perhaps its a trivial question. I was wondering that since all controls have names in the report, is it possible to programatically access values of different textboxes, do some computation and then assign to another text box? I know how to do it using the Aggregate functions and operators, but am not sure if I can access values from textboxes within two different tables and assign the computed value to a third text box on the page (not belonging to any table or other control).



somethig like.... txtTotal.Value = FormatCurrency(txtSalesTotal.Value) - txtDiscount.Value));



Any ideas??



DNG.