How do you know 5 over 8 is in simplest form?

Answer 1

If the GCF of the numerator and denominator is 1, the fraction is in its simplest form as is the case here.
4 and 5 have no common factors other than 1. If the GCF of the numerator and the denominator is 1, the fraction is in its simplest form.

Answer 2

4/5 can be wrote as 2 4/5 but can't be simplified since 5 can't go evenly into 14

Answer 3

Because 5 is a Prime number so it cant divide into anything. eight can only divide into 4 and 2 and five isn't divisible by those numbers.

Answer 4

no because you can still reduce so it would be 1 over 2. :)

Answer 5

2 over 15