This is a quite simple question, and hopefully a simple answer. I know the basics of SR and GR, but I'm bothered by this one. It seems that by adding speeds you can get speeds greater than c. Say we have 4 observers on 4 different bodies. Each observer believes his body to be a rest. We will say that all observers line up to form a straight line progressing from observer 1 -> 4. Observer 1 views observer 2's body to be moving away at 1/2 c. Oberserver 2 views observer 3 to be moving away at 1/2 c. And observer 3 sees observer 4 to be moving away at 1/2 c. This would mean that observer 4 was moving away from observer 1 at 1 1/2 c. How is the universal maximum c not broken here?