Ответ:

  1. \(\frac{2}{4}=\frac{1}{2}\);
  2. \(\frac{5}{15}=\frac{1}{3}\);
  3. \(\frac{6}{10}=\frac{3}{5}\);
  4. \(\frac{8n}{14n}=\frac{4}{7}\), \(n\ne0\).