a) \( \frac{4}{16} : \frac{4}{49} = \frac{4}{16} \cdot \frac{49}{4} = \frac{1}{16} \cdot 49 = \frac{49}{16} \)
б) \( \frac{5}{1} : \frac{9}{18} = 5 \cdot \frac{18}{9} = 5 \cdot 2 = 10 \)
в) \( \frac{12}{8} : \frac{25}{15} = \frac{12}{8} \cdot \frac{15}{25} = \frac{3}{2} \cdot \frac{3}{5} = \frac{9}{10} \)
г) \( \frac{14}{35} = \frac{2 \cdot 7}{5 \cdot 7} = \frac{2}{5} \)
Ответ: а) \( \frac{49}{16} \) б) 10 в) \( \frac{9}{10} \) г) \( \frac{2}{5} \)