Ответ:

  1. \(\frac{14}{20}=\frac{7}{10}\).
  2. \(\frac{9}{63}=\frac{1}{7}\).
  3. \(\frac{33}{77}=\frac{3}{7}\).
  4. \(\frac{15}{75}=\frac{1}{5}\).
  5. \(\frac{36\cdot28}{7\cdot18}=\frac{36}{18}\cdot\frac{28}{7}=2\cdot4=8\).
  6. \(\frac{14\cdot12\cdot17}{36\cdot42\cdot68}=\frac{2\cdot7\cdot12\cdot17}{36\cdot6\cdot7\cdot17}=\frac{24}{216}=\frac{1}{9}\).

Ответ: \(\frac{7}{10};\ \frac{1}{7};\ \frac{3}{7};\ \frac{1}{5};\ 8;\ \frac{1}{9}\).