Ответ:

  1. \(\frac{8}{12}=\frac{8:4}{12:4}=\frac{2}{3}\).
  2. \(\frac{16}{28}=\frac{16:4}{28:4}=\frac{4}{7}\).
  3. \(\frac{25}{60}=\frac{25:5}{60:5}=\frac{5}{12}\).
  4. \(\frac{42}{48}=\frac{42:6}{48:6}=\frac{7}{8}\).
  5. \(\frac{20}{36}=\frac{20:4}{36:4}=\frac{5}{9}\).
  6. \(\frac{34}{54}=\frac{34:2}{54:2}=\frac{17}{27}\).

Ответ: 1) \(\frac{2}{3}\); 2) \(\frac{4}{7}\); 3) \(\frac{5}{12}\); 4) \(\frac{7}{8}\); 5) \(\frac{5}{9}\); 6) \(\frac{17}{27}\).