Вариант 4. Выполните сложение: а) 4/9 + 3/5; б) 7/18 + 7/12; в) 2/9 + 5/18; г) 11/25 + 13/30; д) 5/42 + 1/7; е) 17/20 + 5/12; ж) 5/38 + 7/19; з) 11/21 + 3/14; и) 1/45 + 0,3 + 11/50.

1. \(\frac{4}{9}+\frac{3}{5}=\frac{20}{45}+\frac{27}{45}=\frac{47}{45}=1\frac{2}{45}\).
2. \(\frac{7}{18}+\frac{7}{12}=\frac{14}{36}+\frac{21}{36}=\frac{35}{36}\).
3. \(\frac{2}{9}+\frac{5}{18}=\frac{4}{18}+\frac{5}{18}=\frac{1}{2}\).
4. \(\frac{11}{25}+\frac{13}{30}=\frac{66}{150}+\frac{65}{150}=\frac{131}{150}\).
5. \(\frac{5}{42}+\frac{1}{7}=\frac{5}{42}+\frac{6}{42}=\frac{11}{42}\).
6. \(\frac{17}{20}+\frac{5}{12}=\frac{51}{60}+\frac{25}{60}=\frac{76}{60}=\frac{19}{15}=1\frac{4}{15}\).
7. \(\frac{5}{38}+\frac{7}{19}=\frac{5}{38}+\frac{14}{38}=\frac{19}{38}=\frac{1}{2}\).
8. \(\frac{11}{21}+\frac{3}{14}=\frac{22}{42}+\frac{9}{42}=\frac{31}{42}\).
9. \(\frac{1}{45}+0.3+\frac{11}{50}=\frac{1}{45}+\frac{3}{10}+\frac{11}{50}=\frac{20}{900}+\frac{270}{900}+\frac{198}{900}=\frac{488}{900}=\frac{122}{225}\).

Ответ: а) \(1\frac{2}{45}\); б) \(\frac{35}{36}\); в) \(\frac{1}{2}\); г) \(\frac{131}{150}\); д) \(\frac{11}{42}\); е) \(1\frac{4}{15}\); ж) \(\frac{1}{2}\); з) \(\frac{31}{42}\); и) \(\frac{122}{225}\).