This riddle has been around for some time on internet platforms such as Instagram, Facebook, and WhatsApp, and many people still argue over what the answer might be, as there are many possibilities. The correct answer is 21 students chose neither music nor sports. 20 students chose both subjects, so 35 students chose music only 24 students chose sports only. Therefore, 20 (both) + 35 (music) + 24 (sports) = 79. Number of students who neither took music nor sports: 100 – 79 = 21.