Вопрос:

30. Вычислите: \(6:\frac{18}{23}+2\frac{2}{3}\cdot\left(\frac{3}{14}-4\frac{13}{28}\right)\).

Ответ:

\[6:\frac{18}{23}=6\cdot\frac{23}{18}=\frac{23}{3}.\]

\[\frac{3}{14}-4\frac{13}{28}=\frac{6}{28}-\frac{125}{28}=-\frac{119}{28}=-\frac{17}{4}.\]

\[2\frac{2}{3}\cdot\left(-\frac{17}{4}\right)=\frac{8}{3}\cdot\left(-\frac{17}{4}\right)=-\frac{34}{3}.\]

\[\frac{23}{3}-\frac{34}{3}=-\frac{11}{3}.\]

Ответ: \(-\frac{11}{3}\).