Вычислите:
а) $\frac{3}{20} - \frac{11}{30}$;
б) $\frac{9}{14} + \frac{5}{21}$;
в) $\frac{17}{20} + \frac{19}{30}$;
г) $\frac{16}{21} - \frac{9}{14}$.
$\frac{3}{20} - \frac{11}{30} = \frac{9}{60} - \frac{22}{60} = -\frac{13}{60}$
$\frac{9}{14} + \frac{5}{21} = \frac{27}{42} + \frac{10}{42} = \frac{37}{42}$
$\frac{17}{20} + \frac{19}{30} = \frac{51}{60} + \frac{38}{60} = \frac{89}{60} = 1\frac{29}{60}$
$\frac{16}{21} - \frac{9}{14} = \frac{32}{42} - \frac{27}{42} = \frac{5}{42}$
Пожауйста, оцените решение
