Ответ:

  1. \(\left(\frac{1}{6}+\frac{5}{6}\right)+\left(\frac{5}{9}+\frac{4}{9}\right)=1+1=2\).
  2. \(\left(\frac{2}{17}+\frac{5}{17}+\frac{10}{17}\right)+\left(\frac{3}{8}+\frac{5}{8}\right)=1+1=2\).
  3. \(\left(\frac{1}{12}+\frac{5}{12}\right)+\left(\frac{1}{16}+\frac{7}{16}\right)=\frac{1}{2}+\frac{1}{2}=1\).
  4. \(\left(\frac{3}{17}+\frac{14}{17}\right)+\frac{4}{5}+\frac{1}{15}=1+\frac{12}{15}+\frac{1}{15}=1+\frac{13}{15}=\frac{28}{15}\).

Ответ: а) 2; б) 2; в) 1; г) \(\frac{28}{15}\).