Ответ:

а) \(\frac{4}{7}\cdot\frac{7}{25}=\frac{4}{25}\).

б) \(\frac{2}{3}\cdot\frac{9}{8}=\frac{18}{24}=\frac{3}{4}\).

в) \(\frac{4}{11}\cdot\frac{11}{4}=1\).

г) \(\frac{21}{8}\cdot\frac{13}{14}=\frac{3\cdot13}{8\cdot2}=\frac{39}{16}\).

д) \(\frac{2}{11}\cdot\frac{3}{4}=\frac{3}{22}\).

е) \(\frac{10}{3}\cdot\frac{7}{100}=\frac{7}{30}\).