How do I add two separate select list choices together in one variable?

David Bowen shared this question 4 years ago

I have two select lists with numeric values. I want to add both answers together to determine where to take the user next. So if they select 1 on select list 1, and 2 on select list 2, it should total 3. In that case, I would take them somewhere different upon moving to the next screen than if it added up to 2 or less.