a) $$3 \frac{1}{4} \cdot \frac{4}{9} = \frac{13}{4} \cdot \frac{4}{9} = \frac{13 \cdot 4}{4 \cdot 9} = \frac{13}{9} = 1 \frac{4}{9}$$.
б) $$\frac{3}{4} \cdot \frac{2}{9} = \frac{3 \cdot 2}{4 \cdot 9} = \frac{6}{36} = \frac{1}{6}$$.
в) $$\frac{7}{9} \cdot 5 \frac{2}{5} \cdot \frac{1}{14} = \frac{7}{9} \cdot \frac{27}{5} \cdot \frac{1}{14} = \frac{7 \cdot 27 \cdot 1}{9 \cdot 5 \cdot 14} = \frac{189}{630} = \frac{27}{90} = \frac{3}{10}$$.
Ответ: a) $$1 \frac{4}{9}$$; б) $$\frac{1}{6}$$; в) $$\frac{3}{10}$$