Ответ:

  1. а) \(\frac{2}{27}+\frac{4}{27}+\frac{1}{27}=\frac{2+4+1}{27}=\frac{7}{27}\);
  2. б) \(\frac{4}{45}+\frac{2}{45}+\frac{9}{45}=\frac{4+2+9}{45}=\frac{15}{45}=\frac{1}{3}\);
  3. в) \(\frac{9}{13}-\frac{3}{13}-\frac{4}{13}=\frac{9-3-4}{13}=\frac{2}{13}\);
  4. г) \(\frac{11}{19}-\frac{1}{19}-\frac{2}{19}=\frac{11-1-2}{19}=\frac{8}{19}\).

Ответ: а) \(\frac{7}{27}\); б) \(\frac{1}{3}\); в) \(\frac{2}{13}\); г) \(\frac{8}{19}\).