15/17 can't be simplified. Why and how? Well, first, there is no number that would fit in both 15 and 17 equally. Yes, it would work if you had 16/18, because, 2 goes into both numbers equally so it would be 8/9. But 15/17 cannot be simplified into anything.
Hope this helps u! Im really good with fractions
Cindy7872 AJ