Score showing incorrectly at end

This website has a series of true/false quizzes for seniors. If a quiz taker gets an answer wrong, and then clicks the correct answer to see the explanation, the 2nd click is counting towards the number displayed in the final rating. for example, if someone gets 9/10, but clicks the other answer in the one they got wrong, the final rating will show 10/10 instead of 9/10.

The page I need help with: [log in to see the link]