1. Membalik perbandingan

${\displaystyle \frac{a}{b}}={\displaystyle \frac{2}{5}}$ → ${\displaystyle \frac{b}{a}}={\displaystyle \frac{5}{2}}$

2. Membagi perbandingan

${\displaystyle \frac{a}{b}}={\displaystyle \frac{2}{5}}$ → ${\displaystyle \frac{a}{2}}={\displaystyle \frac{b}{5}}$

3. Kali silang

${\displaystyle \frac{a}{b}}={\displaystyle \frac{2}{5}}$ → $5\times a=2\times b$