Решение:
\[ \frac{11}{24} - \frac{3}{8} = \frac{11}{24} - \frac{3 \cdot 3}{8 \cdot 3} = \frac{11}{24} - \frac{9}{24} = \frac{11 - 9}{24} = \frac{2}{24} = \frac{1}{12} \]
\[ \frac{12}{17} \cdot \frac{1}{12} = \frac{12 \cdot 1}{17 \cdot 12} = \frac{1}{17} \]
Ответ: \(\frac{1}{17}\)