Ответ:
\[4:\frac{20}{23}=\frac{23}{5},\qquad \frac{2}{7}-4\frac{11}{14}=-\frac{9}{2}.\]
\[2\frac{4}{15}\cdot\left(-\frac{9}{2}\right)=\frac{34}{15}\cdot\left(-\frac{9}{2}\right)=-\frac{51}{5}.\]
\[\frac{23}{5}-\frac{51}{5}=-\frac{28}{5}.\]
Ответ: \(-\frac{28}{5}\).
