Ответ:

  1. \(\frac{-48}{-56}=\frac{48}{56}=\frac{6}{7}\).
  2. \(\frac{-64}{-80}=\frac{64}{80}=\frac{4}{5}\).
  3. \(\frac{-121}{55}=-\frac{11}{5}\).
  4. \(\frac{28}{-14}=-2\).

Ответ: 1) \(\frac{6}{7}\); 2) \(\frac{4}{5}\); 3) \(-\frac{11}{5}\); 4) \(-2\).