Ответ:

  1. \(6+\frac{5}{13}=6\frac{5}{13}\).
  2. \(6\frac{4}{9}+5\frac{2}{9}=11\frac{6}{9}=11\frac{2}{3}\).
  3. \(8\frac{7}{18}+7\frac{5}{18}-4\frac{11}{18}=15\frac{12}{18}-4\frac{11}{18}=11\frac{1}{18}\).

Ответ: 1) \(6\frac{5}{13}\); 3) \(11\frac{2}{3}\); 5) \(11\frac{1}{18}\).