Coprime

2 Numbers are relatively prime if: Greatest Common Factor between the 2 numbers is 1. In other words, if $\frac{a}{b}$ cannot be simplified, then you have a relatively prime number

Example 1

5 and 2 are relatively prime since, $\frac{2}{5}$ cannot be simplified more.

Example 2

2 and 6 are NOT relatively prime since $\frac{2}{6}=\frac{1}{3}$. It can be simplified.