How can you tell whether a rational expression is in simplest form? Include an example with your explanation.

A rational in its most simple an be written as a fraction a/b where a and b are co-prime. Which means that there are no common factors in a and b

for example 4/6 is not simplest form because 2 is a factor of 4 and 6

In its simplest form 4/6 is 2/3.