5.411 Вычислите: a) 1/3 + 5/6; б) 5/6 - 1/2; в) 9/10 - 4/5; г) 5/6 - 5/12; д) 11/18 + 1/6; е) 5/12 + 3/4; ж) 4/5 - 7/15; 3) 11/21 + 3/7.

5.411 Вычислите:

a) \( \frac{1}{3} + \frac{5}{6} = \frac{2}{6} + \frac{5}{6} = \frac{7}{6} \)

б) \( \frac{5}{6} - \frac{1}{2} = \frac{5}{6} - \frac{3}{6} = \frac{2}{6} = \frac{1}{3} \)

в) \( \frac{9}{10} - \frac{4}{5} = \frac{9}{10} - \frac{8}{10} = \frac{1}{10} \)

г) \( \frac{5}{6} - \frac{5}{12} = \frac{10}{12} - \frac{5}{12} = \frac{5}{12} \)

д) \( \frac{11}{18} + \frac{1}{6} = \frac{11}{18} + \frac{3}{18} = \frac{14}{18} = \frac{7}{9} \)

е) \( \frac{5}{12} + \frac{3}{4} = \frac{5}{12} + \frac{9}{12} = \frac{14}{12} = \frac{7}{6} \)

ж) \( \frac{4}{5} - \frac{7}{15} = \frac{12}{15} - \frac{7}{15} = \frac{5}{15} = \frac{1}{3} \)

з) \( \frac{11}{21} + \frac{3}{7} = \frac{11}{21} + \frac{9}{21} = \frac{20}{21} \)