Ответ:

Выполняем действия с дробями: при сложении приводим дроби к общему знаменателю, при делении умножаем на обратную дробь.

  1. Е) \(\frac{2}{3}+\frac{5}{9}=\frac{6}{9}+\frac{5}{9}=\frac{11}{9}=1\frac{2}{9}\).
  2. Ё) \(\frac{1}{4}+\frac{2}{25}+\frac{3}{100}=\frac{25}{100}+\frac{8}{100}+\frac{3}{100}=\frac{36}{100}=\frac{9}{25}\).
  3. Ж) \(\frac{1}{45}+\frac{11}{60}=\frac{4}{180}+\frac{33}{180}=\frac{37}{180}\).
  4. З) \(\frac{5}{96}+\frac{3}{16}+\frac{7}{24}=\frac{5}{96}+\frac{18}{96}+\frac{28}{96}=\frac{51}{96}=\frac{17}{32}\).
  5. И) \(6\frac{2}{3}+8\frac{5}{7}=14+\frac{14}{21}+\frac{15}{21}=14\frac{29}{21}=15\frac{8}{21}\).
  6. Л) \(18\cdot\frac{7}{12}=\frac{18}{12}\cdot7=\frac{21}{2}=10\frac{1}{2}\).
  7. М) \(4\frac{2}{7}\cdot3=\frac{30}{7}\cdot3=\frac{90}{7}=12\frac{6}{7}\).
  8. О) \(\frac{8}{21}\cdot\frac{7}{10}=\frac{4}{15}\).
  9. П) \(\frac{1}{3}\cdot4\frac{1}{5}=\frac{1}{3}\cdot\frac{21}{5}=\frac{7}{5}=1\frac{2}{5}\).
  10. С) \(3\frac{3}{5}:5\frac{5}{8}=\frac{18}{5}:\frac{45}{8}=\frac{18}{5}\cdot\frac{8}{45}=\frac{16}{25}\).
  11. Т) \(5\frac{1}{2}\cdot8\frac{1}{11}=\frac{11}{2}\cdot\frac{89}{11}=\frac{89}{2}=44\frac{1}{2}\).
  12. У) \(\left(4\frac{3}{4}\right)^2=\left(\frac{19}{4}\right)^2=\frac{361}{16}=22\frac{9}{16}\).
  13. Ф) \(\frac{20}{27}:5=\frac{20}{27}\cdot\frac{1}{5}=\frac{4}{27}\).
  14. Х) \(57:99=\frac{57}{99}=\frac{19}{33}\).
  15. Ц) \(20:\frac{1}{25}=20\cdot25=500\).
  16. Ч) \(\frac{3}{16}:\frac{5}{12}=\frac{3}{16}\cdot\frac{12}{5}=\frac{9}{20}\).
  17. Ш) \(5\frac{1}{2}:3\frac{2}{3}=\frac{11}{2}:\frac{11}{3}=\frac{3}{2}=1\frac{1}{2}\).
  18. Щ) \(4\frac{3}{8}:5\frac{1}{4}=\frac{35}{8}:\frac{21}{4}=\frac{35}{8}\cdot\frac{4}{21}=\frac{5}{6}\).
  19. Ь) \(\frac{15}{16}\cdot\frac{3}{8}\cdot\frac{3}{4}=\frac{135}{512}\).