а) \(\frac{4}{7} \cdot \frac{7}{25} = \frac{4 \cdot 7}{7 \cdot 25} = \frac{4}{25}\)
б) \(\frac{2}{3} \cdot \frac{3}{8} = \frac{2 \cdot 3}{3 \cdot 8} = \frac{2}{8} = \frac{1}{4}\)
в) \(\frac{4}{11} \cdot \frac{11}{4} = \frac{4 \cdot 11}{11 \cdot 4} = 1\)
г) \(\frac{21}{8} \cdot \frac{10}{14} = \frac{21 \cdot 10}{8 \cdot 14} = \frac{3 \cdot 7 \cdot 2 \cdot 5}{2 \cdot 4 \cdot 2 \cdot 7} = \frac{3 \cdot 5}{4 \cdot 2} = \frac{15}{8}\)
д) \(\frac{23}{11} \cdot \frac{4}{4} = \frac{23 \cdot 4}{11 \cdot 4} = \frac{23}{11}\)
е) \(\frac{10}{3} \cdot \frac{7}{100} = \frac{10 \cdot 7}{3 \cdot 100} = \frac{10 \cdot 7}{3 \cdot 10 \cdot 10} = \frac{7}{3 \cdot 10} = \frac{7}{30}\)
Ответ: а) \(\frac{4}{25}\); б) \(\frac{1}{4}\); в) 1; г) \(\frac{15}{8}\); д) \(\frac{23}{11}\); е) \(\frac{7}{30}\)