What have you tried so far? You know that the number of people is three more than some multiple of thirteen, with the total being between 500 and 600, so you have at least narrowed down the total to a short list of values. You also know that the total was five more than some multiple of nine, which narrowed your list. You know that the total was a multiple of fifteen, or between one and fourteen greater than a multiple of fifteen. What then?
Please be complete. Thank you!