\[\left(-\frac{14}{15}\right)^3=-\frac{2744}{3375}.\]
\[-\frac{7}{9}:\left(-\frac{2744}{3375}\right)=\frac{7}{9}\cdot\frac{3375}{2744}=\frac{125}{56}.\]
\[\frac{125}{56}-1\frac{2}{3}=\frac{125}{56}-\frac{5}{3}=\frac{375-280}{168}=\frac{95}{168}.\]
Ответ: \(\frac{95}{168}\).