1. Выполните действия: a) \(\frac{3}{8} + \frac{1}{8}\); б) \(\frac{9}{11} + \frac{7}{11}\); в) \(\frac{20}{21} + \frac{16}{21}\); г) \(\frac{5}{9} + \frac{2}{9}\); д) \(\frac{7}{10} - \frac{3}{10}\); e) \(\frac{37}{80} - \frac{9}{80}\); ж) \(\frac{7}{25} - \frac{2}{25}\); з) \(\frac{11}{15} - \frac{1}{15} + \frac{2}{15}\);

Решение:

1. \(\frac{3}{8} + \frac{1}{8} = \frac{3+1}{8} = \frac{4}{8} = \frac{1}{2}\)
2. \(\frac{9}{11} + \frac{7}{11} = \frac{9+7}{11} = \frac{16}{11} = 1\frac{5}{11}\)
3. \(\frac{20}{21} + \frac{16}{21} = \frac{20+16}{21} = \frac{36}{21} = \frac{12}{7} = 1\frac{5}{7}\)
4. \(\frac{5}{9} + \frac{2}{9} = \frac{5+2}{9} = \frac{7}{9}\)
5. \(\frac{7}{10} - \frac{3}{10} = \frac{7-3}{10} = \frac{4}{10} = \frac{2}{5}\)
6. \(\frac{37}{80} - \frac{9}{80} = \frac{37-9}{80} = \frac{28}{80} = \frac{7}{20}\)
7. \(\frac{7}{25} - \frac{2}{25} = \frac{7-2}{25} = \frac{5}{25} = \frac{1}{5}\)
8. \(\frac{11}{15} - \frac{1}{15} + \frac{2}{15} = \frac{11-1+2}{15} = \frac{12}{15} = \frac{4}{5}\)

Ответ: а) \(\frac{1}{2}\); б) \(1\frac{5}{11}\); в) \(1\frac{5}{7}\); г) \(\frac{7}{9}\); д) \(\frac{2}{5}\); e) \(\frac{7}{20}\); ж) \(\frac{1}{5}\); з) \(\frac{4}{5}\)