Two sisters have decided to watch all the episodes of a popular TV show on DVD. Eva has already watched 9 episodes and will continue to watch the show at a rate of 3 episodes per day. Kate, who hasn't yet seen the show, will start watching 4 episodes per day. Once the two sisters get to the point where they have watched the same number of episodes, they plan to finish the series together. How many episodes will each sister have watched at that point? How long will that take?