Planet Aniram is similar to Planet Semirg, both of which are perfect sphere. If the ratio of the length of Planet Aniram’s radius to the length of Planet Semirg’s radius is 3:4, then find the volume of Planet Semirg in cubic units if the volume of Planet Aniram is 135 cubic units.

I know how to find the ration, you divide by 3 but I don't know how to find the volume in cubic units.