3. Найдите произведение: 1) $$3\frac{3}{8}\cdot \frac{7}{9}$$; 2) $$4\frac{4}{7}\cdot 2\frac{11}{12}$$; 3) $$1\frac{11}{16}\cdot 3\frac{5}{9}$$; 4) $$1\frac{2}{13}\cdot 5\frac{1}{8}$$.

Разберем каждый пример по отдельности: 1) $$3\frac{3}{8} \cdot \frac{7}{9} = \frac{3 \cdot 8 + 3}{8} \cdot \frac{7}{9} = \frac{27}{8} \cdot \frac{7}{9} = \frac{3 \cdot 9}{8} \cdot \frac{7}{9} = \frac{3}{8} \cdot 7 = \frac{21}{8} = 2\frac{5}{8}$$. 2) $$4\frac{4}{7} \cdot 2\frac{11}{12} = \frac{4 \cdot 7 + 4}{7} \cdot \frac{2 \cdot 12 + 11}{12} = \frac{32}{7} \cdot \frac{35}{12} = \frac{8 \cdot 4}{7} \cdot \frac{5 \cdot 7}{3 \cdot 4} = \frac{8}{1} \cdot \frac{5}{3} = \frac{40}{3} = 13\frac{1}{3}$$. 3) $$1\frac{11}{16} \cdot 3\frac{5}{9} = \frac{1 \cdot 16 + 11}{16} \cdot \frac{3 \cdot 9 + 5}{9} = \frac{27}{16} \cdot \frac{32}{9} = \frac{3 \cdot 9}{16} \cdot \frac{2 \cdot 16}{9} = 3 \cdot 2 = 6$$. 4) $$1\frac{2}{13} \cdot 5\frac{1}{8} = \frac{1 \cdot 13 + 2}{13} \cdot \frac{5 \cdot 8 + 1}{8} = \frac{15}{13} \cdot \frac{41}{8} = \frac{15 \cdot 41}{13 \cdot 8} = \frac{615}{104} = 5\frac{95}{104}$$.