Найдите значение выражения: (9/14-(-5/21)):(-2 9/14).

\[\left( \frac{9}{14} - \left( - \frac{5}{21} \right) \right)\ :\left( - 2\frac{9}{14} \right) =\]

\[= \left( \frac{9}{14} + \frac{5}{21} \right)\ :\left( - \frac{37}{14} \right) =\]

\[= \frac{27 + 10}{42} \cdot \left( - \frac{14}{37} \right) =\]

\[= - \frac{37 \cdot 14}{42 \cdot 37} = - \frac{1}{3}\]