Ответ:

  1. \(2\frac{1}{7}+3\frac{4}{7}=5\frac{5}{7}\).
  2. \(4\frac{5}{9}+1\frac{7}{9}=5\frac{12}{9}=6\frac{1}{3}\).
  3. \(1\frac{1}{4}+2\frac{1}{6}=1\frac{3}{12}+2\frac{2}{12}=3\frac{5}{12}\).
  4. \(5\frac{7}{8}-2\frac{3}{8}=3\frac{4}{8}=3\frac{1}{2}\).
  5. \(4-1\frac{2}{5}=3\frac{5}{5}-1\frac{2}{5}=2\frac{3}{5}\).