since i am new at learning special relativity, i still miss the concept about how thing move in special relativity. In highschool, i am doing several problem about velocity addition, and that word always appear. for example: A is moving with velocity vAO relative to O, and B is moving with velocity vBO relative to O, what is A velocity relative to B? and then i am using formula VAB=(VAO+VOB)/(1+VAO.VOB/c2) and then you get the answer but i can't really understand it. So i try to draw it (in this image, i just draw object O and A (without B), so i can understand what VAO really mean) (let say that A is travelling 0.5c from our viewpoint) so, VAO will be 1/3 c because O see A only travel 1.5x108m after 1.5 second (or 3x108m after 3 second), is this what we say A is moving relative to O?