I have created two commands in the database expert. And I want to do the calulation of these records.

My situation is:

In table A, I have fields "Country","Amount" and "Currency".
In table B, I have fields "Currency" and "Exchange".

I want get the sum of "Amount"*"Exchange" if table A "Currency" = table B "Currency" that group by "Country"

How to write this formula?

Thank you fro helping me.