Решение:
- \( \frac{5}{8} \cdot \frac{4}{15} = \frac{5 \cdot 4}{8 \cdot 15} = \frac{20}{120} = \frac{1}{6} \)
- \( 6\frac{3}{4} \cdot 1\frac{1}{45} = \frac{27}{4} \cdot \frac{46}{45} = \frac{27 \cdot 46}{4 \cdot 45} = \frac{1242}{180} = \frac{69}{10} = 6\frac{9}{10} \)
- \( \frac{11}{18} \cdot 36 = \frac{11 \cdot 36}{18} = 11 \cdot 2 = 22 \)
Ответ: 1) \( \frac{1}{6} \); 2) \( 6\frac{9}{10} \); 3) 22.