Except 5/20. This is because in the other fractions, you can multiply the numerator by 5 to get the denominator other than 5/20. To show you, 8•5=40, 3•5=15, 6•5=30, and 5•4=20. In other cases, to see if it is equivalent then you would have to divide or multiply the numerator and denominator by the same number, like multiplying the 5 and 20 from the fraction 5/20 by 6 (or a different number). This is not the case though.
