24. Вычислите: a) \( \frac{5}{6} + \frac{2}{7} \) г) \( \frac{3}{20} + \frac{7}{15} \) б) \( \frac{11}{25} - \frac{3}{10} \) д) \( \frac{13}{16} - \frac{7}{12} \) е) \( \frac{15}{16} - \frac{3}{4} \) и) \( \frac{9}{14} + \frac{5}{21} \)

Решение:

а)

\( \frac{5}{6} + \frac{2}{7} = \frac{5 \times 7 + 2 \times 6}{6 \times 7} = \frac{35 + 12}{42} = \frac{47}{42} = 1 \frac{5}{42} \)

б)

\( \frac{11}{25} - \frac{3}{10} = \frac{11 \times 2 - 3 \times 5}{50} = \frac{22 - 15}{50} = \frac{7}{50} \)

в)

\( \frac{3}{20} + \frac{7}{15} = \frac{3 \times 3 + 7 \times 4}{60} = \frac{9 + 28}{60} = \frac{37}{60} \)

г)

\( \frac{13}{16} - \frac{7}{12} = \frac{13 \times 3 - 7 \times 4}{48} = \frac{39 - 28}{48} = \frac{11}{48} \)

д)

\( \frac{15}{16} - \frac{3}{4} = \frac{15 - 3 \times 4}{16} = \frac{15 - 12}{16} = \frac{3}{16} \)

е)

\( \frac{9}{14} + \frac{5}{21} = \frac{9 \times 3 + 5 \times 2}{42} = \frac{27 + 10}{42} = \frac{37}{42} \)

Ответ: а) \( 1 \frac{5}{42} \); б) \( \frac{7}{50} \); в) \( \frac{37}{60} \); г) \( \frac{11}{48} \); д) \( \frac{3}{16} \); е) \( \frac{37}{42} \).