Which fraction is bigger 58 or 715?

assuming you mean 5/8 and 7/15 it would be 5/8. You can do this 2 ways.

Either figure out half of each 4/8 and 7.5/15 realize that 5/8 is more than half and 7/15 is less than half. The other way is to just do 5 divided by 8 and 7 divided by 15