2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/187305We deduce the most general space-time transformation laws consistent with the principle of relativity. Thus, our result contains the results of both Galilean and Einsteinian relativity. The velocity addition law comes as a bi-product of this analysis. We also argue why Galilean and Einsteinian versions are the only possible embodiments of the principle of relativity.6 pages, LatexClassical PhysicsGeneral Physicstext