Since the direct ratio for 9 + 10 averages to about 21 in modern pop culture, but the true answer is 19, you would round that to the closest number in between, that being about 1.5 + 19 making it 20.5 because it is in between the literal answer and the phenomenon of the viral video, therefore rewriting both answers in a very indirect, yet plausible effort that defies all laws of physics, and represents the human mind as a whole. From Einsteins reasoning of it, it is called pym particles. It tells us and explains why we find enjoyement in such concepts. For example, saying that we cannot defy gravity is a stretch, but also very likeways and most likely the correct alternative to saying that we could, indeed defy gravity. If You were to say what is 9+10, and the answer I would say is 21 is incorrect, but that is based on what society tells us. If I were to say what is 9+10 where you say 19, It would have no evidence backing up the statement. Therefore, the answer to everything is not what the mind tells us, it is what we are induced by teachers, in which case, how are the teachers correct. We cannot say unless god himself tells us the answer. For now I would like you to believe that my best answer for you, at this point in time, after you have taken in the meaning of everything I have explained, is 20.5. If you want the answer I you would like to hear then... 21. I hope I have taught you something, although I am only 13. Or am I. It is what we learn, but could, very well, just be a joke from the very first mathmatician Pythagoras. Haha funny joke Pythagoras. Or at least I think it is funny...?