1. The problem statement, all variables and given/known data Two spaceships approach the Earth from opposite directions. According to an observer on the Earth, ship A is moving at a speed of .753c and ship B at a speed of .851c. What is the speed of ship A as observed from ship B? Of ship B as observed from ship A? 2. Relevant equations v'=(v-u)/(1-u*v/c^2) 3. The attempt at a solution For the speed of ship A with respect to B I tried (.851c-.753c)/(1-.851c*.753c/c^2) = .2728c For the speed of ship B with respect to A i tried (.851c+.753c)/(1+.851c*.753c/c^2) = .9776c I am not sure of the correct answers, However I'm pretty sure these are wrong. Thanks.