1. The problem statement, all variables and given/known data I came across this problem in a worksheet and I am completely lost as to where to start; can someone help? The question is: Two trains are heading at the same speed, relative to the Earth, in opposite directions. A bomb explodes on each train, but not at the same times. An observer on train A says that the x-coordinate of bomb A was twice that of bomb B. An observer on train B, using the same origin and orientation, says that the x-coordinate of bomb B was twice that of bomb A. However, they agree on the time coordinates: bomb A's time coordinate was twice that of bomb B's. What are the x-coordinates of the bombs' explosions as measured by train B? 2. Relevant equations x=x'-vt? 3. The attempt at a solution I have no clue where to start; this problem doesn't make sense to me and I need some help to actually start this problem.