Ответ:

а) \(\frac{13}{18}+\frac{7}{12}=\frac{26}{36}+\frac{21}{36}=\frac{47}{36}=1\frac{11}{36}\).

б) \(\frac{5}{7}-\frac{3}{5}=\frac{25}{35}-\frac{21}{35}=\frac{4}{35}\).

в) \(3\frac{4}{7}-2\frac{3}{5}=\frac{25}{7}-\frac{13}{5}=\frac{125}{35}-\frac{91}{35}=\frac{34}{35}\).

г) \(6\frac{5}{6}+2\frac{3}{8}=8+\frac{20}{24}+\frac{9}{24}=8+\frac{29}{24}=9\frac{5}{24}\).

Ответ: а) \(1\frac{11}{36}\); б) \(\frac{4}{35}\); в) \(\frac{34}{35}\); г) \(9\frac{5}{24}\).