Найдите значение выражения:
а) $\frac{4}{7} * \frac{5}{24} : 1\frac{1}{14}$;
б) $25 * \frac{7}{15} : \frac{7}{9}$;
в) $\frac{7}{18} : \frac{20}{21} : \frac{5}{12}$;
г) $\frac{5}{9} * 2\frac{1}{4} : 20$.
$\frac{4}{7} * \frac{5}{24} : 1\frac{1}{14} = \frac{1}{7} * \frac{5}{6} : \frac{15}{14} = \frac{5}{42} * \frac{14}{15} = \frac{1}{3} * \frac{1}{3} = \frac{1}{9}$
$25 * \frac{7}{15} : \frac{7}{9} = 5 * \frac{7}{3} * \frac{9}{7} = 5 * \frac{1}{1} * \frac{3}{1} = 15$
$\frac{7}{18} : \frac{20}{21} : \frac{5}{12} = \frac{7}{18} * \frac{21}{20} * \frac{12}{5} = \frac{7}{1} * \frac{7}{10} * \frac{1}{5} = \frac{49}{50}$
$\frac{5}{9} * 2\frac{1}{4} : 20 = \frac{5}{9} * \frac{9}{4} * \frac{1}{20} = \frac{1}{1} * \frac{1}{4} * \frac{1}{4} = \frac{1}{16}$