a) $$\frac{2}{7} \cdot 3 = \frac{2 \cdot 3}{7} = \frac{6}{7}$$
б) $$8 \cdot \frac{5}{16} = \frac{8 \cdot 5}{16} = \frac{40}{16} = \frac{5}{2} = 2\frac{1}{2}$$
в) $$\frac{4}{5} \cdot 30 = \frac{4 \cdot 30}{5} = \frac{120}{5} = 24$$
г) $$\frac{6}{23} \cdot 0 = 0$$
д) $$\frac{18}{29} \cdot 1 = \frac{18}{29}$$