\[\left( \frac{11}{16} - \left( - \frac{17}{24} \right) \right)\ :\left( - 5\frac{7}{12} \right) =\]
\[= \left( \frac{33}{48} + \frac{34}{48} \right)\ :\left( - \frac{67}{12} \right) =\]
\[= - \frac{67 \cdot 12}{48 \cdot 67} = - \frac{1}{4}\]