how to over come dynamic sql in Oracle Forms?

Hi 

We are migrating our 6i forms  to 11g forms.

we had a situation like we will ask user to enter a function which means in which arithmetic operations may also get included..

for examle:-user enters the below function {{A+B}/{D-C}} .Later we will ask the user to give the values for  each A,B,C,D this was done previously by using Dynamic SQL 

now as 11g forms wont support that can any one please suggest how to go over come this situation?

Thanks in Advance

Regards

Kartheek