The other guy figured out he was good at math, but he had never seen Billy work on his equations, that wasn't easy to do and no kid does equations for fun or because they want to. So the other kid went to the gym to practice and take his mind off math, and sure enough, there was Billy at the gym practicing too. The other guy thought he was more devoted than Billy to
everything, and therefore better at
everything, but Billy kept struggling with him to let him know he was just as good at math or physical activities, not better, but just as good.