Ответ:

  1. \(\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{1}{2}=\frac{1}{4}\).
  2. \(\frac{5}{6}\cdot\frac{2}{3}\cdot\frac{4}{5}=\frac{8}{18}=\frac{4}{9}\).
  3. \(\frac{1}{2}\cdot\frac{8}{9}\cdot\frac{4}{3}=\frac{16}{27}\).
  4. \(\frac{7}{12}:\frac{7}{8}\cdot\frac{3}{4}=\frac{7}{12}\cdot\frac{8}{7}\cdot\frac{3}{4}=\frac{1}{2}\).