Summing values based on radio button selection

Good Day,
 
I am creating a form in which I have a table with a text field where a user will input an Amount, these fields are named Amount.n where n is the row number. I also have 6 radio buttons on each row with export values of 1-6, named rb.n where n is again the row number. What I wish to accomplish is a text field at the bottom of each radio button column that sums the values the user has inputted in the Amount column only if the radio button is selected for that row.
 
I've scoured the internet and these forums for topics to this regard without any luck. Any help would be greatly appreciated .
 
Thanks
 
Steve.