Ответ:

  1. \(\frac{2}{3}+\frac{4}{5}=\frac{10}{15}+\frac{12}{15}=\frac{22}{15}=1\frac{7}{15}\).
  2. \(\frac{3}{7}+\frac{5}{7}=\frac{8}{7}=1\frac{1}{7}\).
  3. \(\frac{3}{5}+\frac{4}{7}=\frac{21}{35}+\frac{20}{35}=\frac{41}{35}=1\frac{6}{35}\).
  4. \(\frac{2}{9}+\frac{3}{5}=\frac{10}{45}+\frac{27}{45}=\frac{37}{45}\).
  5. \(1\frac{2}{3}+2\frac{1}{4}=4+\frac{8}{12}+\frac{3}{12}=4\frac{11}{12}\).
  6. \(3\frac{1}{3}+4\frac{2}{5}=7+\frac{5}{15}+\frac{6}{15}=7\frac{11}{15}\).
  7. \(\frac{3}{5}-\frac{1}{5}=\frac{2}{5}\).
  8. \(\frac{4}{7}-\frac{6}{7}=-\frac{2}{7}\).
  9. \(\frac{5}{7}-\frac{3}{5}=\frac{25}{35}-\frac{21}{35}=\frac{4}{35}\).
  10. \(\frac{7}{9}-\frac{9}{10}=\frac{70}{90}-\frac{81}{90}=-\frac{11}{90}\).
  11. \(4\frac{1}{3}-3\frac{1}{5}=1+\frac{5}{15}-\frac{3}{15}=1\frac{2}{15}\).
  12. \(2\frac{1}{4}-3\frac{1}{2}=\frac{9}{4}-\frac{14}{4}=-\frac{5}{4}=-1\frac{1}{4}\).
  13. \(5\frac{1}{6}-2\frac{1}{4}=3+\frac{2}{12}-\frac{3}{12}=2\frac{11}{12}\).
  14. \(3\frac{1}{7}-1\frac{1}{3}=2+\frac{3}{21}-\frac{7}{21}=1\frac{17}{21}\).

Ответ: а) \(1\frac{7}{15}\); б) \(1\frac{1}{7}\); в) \(1\frac{6}{35}\); г) \(\frac{37}{45}\); д) \(4\frac{11}{12}\); е) \(7\frac{11}{15}\); ж) \(\frac{2}{5}\); з) \(-\frac{2}{7}\); и) \(\frac{4}{35}\); к) \(-\frac{11}{90}\); л) \(1\frac{2}{15}\); м) \(-1\frac{1}{4}\); н) \(2\frac{11}{12}\); о) \(1\frac{17}{21}\).