Решение:

1. a) $$\frac{1}{2} \cdot \frac{2}{3} = \frac{1 \cdot 2}{2 \cdot 3} = \frac{2}{6} = \frac{1}{3}$$
2. б) $$\frac{2}{6} \cdot \frac{6}{7} = \frac{2 \cdot 6}{6 \cdot 7} = \frac{12}{42} = \frac{2}{7}$$
3. в) $$\frac{7}{8} \cdot \frac{24}{49} = \frac{7 \cdot 24}{8 \cdot 49} = \frac{168}{392} = \frac{3}{7}$$
4. г) $$\frac{100}{121} \cdot \frac{55}{144} = \frac{100 \cdot 55}{121 \cdot 144} = \frac{5500}{17424} = \frac{125}{396}$$
5. д) $$\frac{3}{8} \cdot 2 = \frac{3 \cdot 2}{8} = \frac{6}{8} = \frac{3}{4}$$
6. e) $$\frac{4}{5} \cdot 6 = \frac{4 \cdot 6}{5} = \frac{24}{5} = 4\frac{4}{5}$$
7. ж) $$3 \cdot 1\frac{1}{8} = 3 \cdot \frac{1 \cdot 8 + 1}{8} = 3 \cdot \frac{9}{8} = \frac{3 \cdot 9}{8} = \frac{27}{8} = 3\frac{3}{8}$$
8. з) $$0 \cdot \frac{1}{4} = 0$$
9. и) $$4 \cdot 2\frac{1}{12} = 4 \cdot \frac{2 \cdot 12 + 1}{12} = 4 \cdot \frac{25}{12} = \frac{4 \cdot 25}{12} = \frac{100}{12} = \frac{25}{3} = 8\frac{1}{3}$$

Ответы:

• a) $$\frac{1}{3}$$
• б) $$\frac{2}{7}$$
• в) $$\frac{3}{7}$$
• г) $$\frac{125}{396}$$
• д) $$\frac{3}{4}$$
• e) $$4\frac{4}{5}$$
• ж) $$3\frac{3}{8}$$
• з) $$0$$
• и) $$8\frac{1}{3}$$