1. The problem statement, all variables and given/known data The coordinates of events E1 and E2 in frame S are E1: x=0, t=0 E2: x=8 light seconds t=10 sec In some frame S'', E1 and E2 occur at the same place. Find the velocity of S'' relative to S. 2. Relevant equations How should I start the problem? Am I using equation correctly? 3. The attempt at a solution I attempted using the Lorentz Transformation for time: Δt’’ = γ(Δt - VΔx/c^2). Since the events are supposed to be simultaneous in frame S'', I set t'' to 0. What's left is setting what is in the parentheses equal to 0. I do that, but I get V = 10/8 = 1.25. That would be 1.25c, which obviously isn't possible.