12/17 is greater than 5/8 because to determine which fraction is greater you need to have the same denominator. To get the same denominator I multiplied 17 by 8 and 8 by 17. Since what you do the denominator you have to do the same to the numerator, you would multiply 12 by 8 and 5 by 17 which would lead you to get 12/17= 96/136 and 5/8= 85/136. So, 96/136 > 85/136.
