If we have 500 people, and all of them must take a seat, and in each row, we have 28 seats, then we need to divide the total of people by the total of seats by row. Then, we have the total number for rows:
Therefore, we will have 18 rows (of 28 seats each) to have the 500 people seated.
If we check the answer:
18 * 28 seats = 504 seats (we will have four more seats for people to get seated).