a) \frac{20}{14} = \frac{20 ∶ 2}{14 ∶ 2} = \frac{10}{7}
б) \frac{4}{6} = \frac{4 ∶ 2}{6 ∶ 2} = \frac{2}{3}
в) \frac{18}{22} = \frac{18 ∶ 2}{22 ∶ 2} = \frac{9}{11}
г) \frac{2}{10} = \frac{2 ∶ 2}{10 ∶ 2} = \frac{1}{5}
Ответ: a) \frac{10}{7}; б) \frac{2}{3}; в) \frac{9}{11}; г) \frac{1}{5}