Hope this helps:
you know O is in the last row
since P is beside R and an X, it has to be XPR or RPX... and that means, it can also NOT be in the last row, as O is already there.
Then you read that R is in a row behind N, so since R cannot be in the 3rd row, the XPR/RPX has to be in the second row, and N is in the first row. (X being an empty seat)
that's how you get the setup explained above.
You must keep in mind the rule that S&U cannot sit next to N to answer a majority of the questions.
Realize though, that DOES NOT mean that neither S&U cannot be in the first row with N, however, only one of them can be.
Hopefully this helped!
