1. The problem statement, all variables and given/known data Two asteroids are approaching one another moving with the same speed speed as measured from a stationary observer on Europa. Their relative speed is 0.5c. Find the speed of one of asteroids relative to Europa. I understand how relativistic velocity addition works but am not able to solve this question. Is it possible there is not enough information given in the problem? Any help would be much appreciated. 2. Relevant equations u = (u' + v) / (1 + (u'v)/c^2) 3. The attempt at a solution The ambiguity of the problem statement has led me down several different paths each resulting in a quadratic that in most cases results in a speed faster than c.