If we arrange the seats in r rows with s seats in each row, we have

Since the number of rows is 6 less than the number of seats in each row, we have

Substitute this in the first equation to get

This equation has solutions -28 and 34. We can't accept negative solutions (we would have -28 seats in each row...what would that mean??), the only feasible solution is 34.
So, we have

rows with 34 seats per row.