Ответ:

  1. \(\frac{5}{3}:\frac{9}{2}=\frac{5}{3}\cdot\frac{2}{9}=\frac{10}{27}\).
  2. \(\frac{7}{5}\cdot\frac{12}{35}=\frac{84}{175}=\frac{12}{25}\).
  3. \(\frac{21}{2}:\frac{3}{5}=\frac{21}{2}\cdot\frac{5}{3}=\frac{35}{2}\).
  4. \(\frac{14}{5}:\frac{7}{2}=\frac{14}{5}\cdot\frac{2}{7}=\frac{4}{5}\).
  5. \(\frac12-\frac{13}{50}=\frac{25}{50}-\frac{13}{50}=\frac{12}{50}=\frac{6}{25}\).
  6. \(\frac1{10}-\frac{23}{20}=\frac2{20}-\frac{23}{20}=-\frac{21}{20}\).
  7. \(\frac34+\frac7{25}=\frac{75}{100}+\frac{28}{100}=\frac{103}{100}\).
  8. \(\frac4{25}+\frac{15}{4}=\frac{16}{100}+\frac{375}{100}=\frac{391}{100}\).

Ответ: 5) \(\frac{10}{27}\); 6) \(\frac{12}{25}\); 11) \(\frac{35}{2}\); 12) \(\frac45\); 17) \(\frac6{25}\); 18) \(-\frac{21}{20}\); 23) \(\frac{103}{100}\); 24) \(\frac{391}{100}\).