This year the music school has 85 students last year it had 17 students how many times greater is this years number of students?

It would be 68 students more because if you subtract 17 from 85 you would get 68

It is 5 times greater.  To find this answer, you need to find how many times 17 goes into 85.  You can do this by writing out all multiples of 17, finding it using fractions or some other ways.  If you want to write out the multiples, start at 17 then add 17 for each multiple.  So it would be 17, 17+17, 17+17+17, etc.  When doing this, you would get 17, 34, 51, 68, 85.  85 is the fifth multiple of 17 (or 17×5), so that is the answer.  Another way to solve is to divide.  Divide 85 by 17 to get 85/17, or 5.  Hope this was helpful!