1. Выполните действия: a) \(\frac{3}{5}+\frac{1}{5}\); б) \(\frac{5}{18}+\frac{7}{18}\); в) \(\frac{18}{23}+\frac{6}{23}\); г) \(\frac{2}{9}+\frac{4}{9}\); д) \(\frac{17}{20}+\frac{3}{20}\); е) \(\frac{51}{100}-\frac{9}{100}\); ж) \(\frac{11}{45}-\frac{2}{45}\); з) \(\frac{11}{25}-\frac{9}{25}+\frac{2}{25}\);

Решение:

1. a) \(\frac{3}{5}+\frac{1}{5} = \frac{3+1}{5} = \frac{4}{5}\)
2. б) \(\frac{5}{18}+\frac{7}{18} = \frac{5+7}{18} = \frac{12}{18} = \frac{2}{3}\)
3. в) \(\frac{18}{23}+\frac{6}{23} = \frac{18+6}{23} = \frac{24}{23} = 1\frac{1}{23}\)
4. г) \(\frac{2}{9}+\frac{4}{9} = \frac{2+4}{9} = \frac{6}{9} = \frac{2}{3}\)
5. д) \(\frac{17}{20}+\frac{3}{20} = \frac{17+3}{20} = \frac{20}{20} = 1\)
6. е) \(\frac{51}{100}-\frac{9}{100} = \frac{51-9}{100} = \frac{42}{100} = \frac{21}{50}\)
7. ж) \(\frac{11}{45}-\frac{2}{45} = \frac{11-2}{45} = \frac{9}{45} = \frac{1}{5}\)
8. з) \(\frac{11}{25}-\frac{9}{25}+\frac{2}{25} = \frac{11-9+2}{25} = \frac{4}{25}\)

Ответ: a) \(\frac{4}{5}\); б) \(\frac{2}{3}\); в) \(1\frac{1}{23}\); г) \(\frac{2}{3}\); д) 1; е) \(\frac{21}{50}\); ж) \(\frac{1}{5}\); з) \(\frac{4}{25}\)