First you have to make the fractions have like denominators to efficiently compare these fractions. 5 and 8 have a common denominator of 40, so you have to multiply top and bottom by 8 for 4/5 and by 5 for 6/8.
4/5 * 8/8 = 32/40
6/8 * 5/5 = 30/40
This shows that 4/5 is greater than 6/8. 4/5 > 6/8
