1. Решение:
- \(\frac{5}{8} \cdot \frac{4}{15} = \frac{5 \cdot 4}{8 \cdot 15} = \frac{20}{120} = \frac{1}{6}\)
- \(6\frac{3}{4} \cdot 1\frac{11}{45} = \frac{27}{4} \cdot \frac{56}{45} = \frac{27 \cdot 56}{4 \cdot 45} = \frac{3 \cdot 9 \cdot 4 \cdot 14}{4 \cdot 5 \cdot 9} = \frac{3 \cdot 14}{5} = \frac{42}{5} = 8\frac{2}{5}\)
- \(\frac{11}{18} \cdot 36 = \frac{11 \cdot 36}{18} = 11 \cdot 2 = 22\)
Ответ: 1) $$\frac{1}{6}$$; 2) $$8\frac{2}{5}$$; 3) 22.