Answer:
17 students per teacher, 9 students per tutor. You need 10 tutors if the school had 90 students.
Explanation:
51 students divided by 3 teachers = 17 students per teacher.
45 students divided by 5 tutors = 9 students per teacher.
If there are 9 students per tutor 9 * 10 = 90 so ten tutors