4) \(\frac{25}{36}\) : \(\frac{5}{18}\) = \(\frac{50}{27}\) \(\frac{27}{50}\) : \(\frac{9}{10}\) = \(\frac{3}{5}\) \(\frac{21}{72}\) : \(\frac{3}{4}\) = \(\frac{7}{24}\) \(\frac{45}{49}\) : \(\frac{15}{21}\) = \(\frac{21}{7}\) \(\frac{18}{24}\) : \(\frac{3}{4}\) = \(\frac{3}{4}\)

Решение:

Примеры на деление обыкновенных дробей:

1. \(\frac{25}{36} : \frac{5}{18} = \frac{25}{36} \times \frac{18}{5} = \frac{5}{2} \times \frac{1}{1} = \frac{5}{2}\)
2. \(\frac{27}{50} : \frac{9}{10} = \frac{27}{50} \times \frac{10}{9} = \frac{3}{5}\)
3. \(\frac{21}{72} : \frac{3}{4} = \frac{21}{72} \times \frac{4}{3} = \frac{7}{18} \times \frac{1}{1} = \frac{7}{18}\)
4. \(\frac{45}{49} : \frac{15}{21} = \frac{45}{49} \times \frac{21}{15} = \frac{3}{7} \times \frac{3}{1} = \frac{9}{7}\)
5. \(\frac{18}{24} : \frac{3}{4} = \frac{18}{24} \times \frac{4}{3} = \frac{3}{2} \times \frac{1}{1} = \frac{3}{2}\)

Ответ: \(\frac{5}{2}\), \(\frac{3}{5}\), \(\frac{7}{18}\), \(\frac{9}{7}\), \(\frac{3}{2}\).