1. The problem statement, all variables and given/known data Two events occur at the same place in an inertial reference fram S, but are separated in time by 3 seconds. In a different frame S', they are separated in time by 4 seconds. (a) What is the distance between the two events as measured in S'? (b) What is the speed of S relative to S'? 2. Relevant equations I'm presuming: t' = gamma*(t-ux/c^2) 3. The attempt at a solution I have the answer, and a hint saying to use the interval S^2, but I have no idea what that means, and where I start. When I look and the relevant Lorentz equations, they involve velocity, and I do not have a velocity here. Could you please point me in the right direction? Thank you in advance.