Rule 4

As explained in the video explanation for the setup of this game, which you can access by tapping the "play" button and choosing "game setup," we know from rule number 1 that the computer in each office was bought either in an earlier year than or in the same year as the printer in that office. Rule number 5 tells us that the computer in office 1 was purchased in 1988. So, this means that the printer in office 1 cannot be from an earlier year than 1988, i.e. it was purchased in either 1988 or 1989. We also know from rule number 2 that the computer in office 2 and the printer in office 1 were bought in the same year. So, since we made the deduction that the printer in office 1 can only be from wither 1988 or 1989, then we know that the computer in office 2 is going to be from the same year: either 1988 or 1989. Hope that clears things up! Please let us know if you have any other questions.