We calculate the number of students by dividing the cost with the cost per student. So we have: (624/(X - 13)) = (624/X) + 8 --> Multiply both sides with (X)(X - 13) --> 624(X) = 624(X - 13) + 8(X)(X - 13) --> 624X = 624X - 8112 + 8X^2 - 104X --> 0 = 8X^2 - 104X - 8112 --> X = 39,-26. Since there are no negative number of people, we get 39. To get the number of students in the bus: X = 39 - 13 = 26 students.