Populating summary box only when activator field is triggered

I have a questionaire with a series of numbers that I am calculating with the (Sum +) function. But I use the same questions (and values) for two different situations. One questionaire series when using a walking cane, for example, and one series when not using a walking cane. I realize that the summary boxes (2 of them) will always be calculated and filled in as the form is populated using the (Sum + function), as I have it arranged now. What I would like to do is use a trigger selector (with cane, and without cane) so that a summary box at the bottom of the form is only calculated when the selector radio button (with cane or without cane) is active. I'm not a javascript user, as yet, but am wondering if this form can be calculated using something other than javascript. I am familiar with if, then, else, loops, etc., coding, but am not an active programmer. I realize I need to get busy with Javascript. Thanks for your suggestions or referrals.