1. The problem statement, all variables and given/known data At the bottom of this page: http://www.cv.nrao.edu/course/astr534/LorentzTransform.html It states; Lorentz factor: * y =gamma How did they eliminate x? 3. The attempt at a solution I'm taking the x value which is y(x'+vt') and substituting this into the x value in the x' equation. So I'm getting; x' = y^2(x'+vt')-yvt Then I've separated the equation so that t is on LHS; t = [y^2(x' + vt')] / yv If anyone knows how this is done, I'd be very interested in learning! Thank you.