Ответ:

  1. а) Перемножаем числители и знаменатели: \(\frac{1}{3}\times\frac{6}{7}=\frac{6}{21}=\frac{2}{7}\).
  2. б) \(\frac{2}{7}\times\frac{6}{7}=\frac{12}{49}\).
  3. в) \(\frac{3}{5}\times\frac{7}{8}=\frac{21}{40}\).
  4. г) \(\frac{3}{4}\times\frac{7}{12}=\frac{21}{48}=\frac{7}{16}\).
  5. д) \(\frac{13}{13}\times\frac{26}{39}=1\times\frac{2}{3}=\frac{2}{3}\).
  6. е) \(\frac{5}{11}\times\frac{55}{77}=\frac{275}{847}=\frac{25}{77}\).
  7. ж) \(\frac{2}{3}\times\frac{6}{14}=\frac{12}{42}=\frac{2}{7}\).
  8. з) \(\frac{2}{9}\times\frac{3}{10}=\frac{6}{90}=\frac{1}{15}\).