Simplify by dividing a common factor (5). 15/24. Check to see if it can be simplified. Repeat (using 3). 5/8. Check to see if it can be simplified. It can't, so the answer is 5/8
If you Divide 5 by 75/120 it equals 15/24 then divide 3 by 15/24 and you get 5/8 which is the answer because you can't simplify no more. (Sorry I was thinking as I was explaining)