Ответ:

  1. \(\frac{3x^2}{7x}=\frac{3x}{7}\);
  2. \(\frac{8y^3}{15y^4}=\frac{8}{15y}\);
  3. \(\frac{-4x^2}{-8x^3}=\frac{1}{2x}\);
  4. \(\frac{2a^5}{a^4}=2a\);
  5. \(\frac{-14b^2}{21b^4}=-\frac{2}{3b^2}\);
  6. \(\frac{27c^6}{45c}=\frac{3c^5}{5}\).

Ответ: а) \(\frac{3x}{7}\); б) \(\frac{8}{15y}\); в) \(\frac{1}{2x}\); г) \(2a\); д) \(-\frac{2}{3b^2}\); е) \(\frac{3c^5}{5}\).