Решение:
\[ 11\frac{5}{11} - 8\frac{21}{22} = \frac{126}{11} - \frac{197}{22} = \frac{126 \times 2}{11 \times 2} - \frac{197}{22} = \frac{252}{22} - \frac{197}{22} = \frac{55}{22} \]
\[ \frac{55}{22} = \frac{5 \times 11}{2 \times 11} = \frac{5}{2} \]
\[ \frac{5}{2} : 1\frac{2}{3} = \frac{5}{2} : \frac{5}{3} = \frac{5}{2} \times \frac{3}{5} = \frac{3}{2} = 1\frac{1}{2} \]
Ответ: \[ 1\frac{1}{2} \]