Решите примеры с обыкновенными дробями: умножение и деление.

**Ответы:** **Столбец 1:** 1. $\frac{2}{5} \cdot \frac{3}{4} = \frac{2 \cdot 3}{5 \cdot 4} = \frac{6}{20} = \frac{3}{10}$ 2. $\frac{1}{7} \cdot \frac{2}{3} = \frac{1 \cdot 2}{7 \cdot 3} = \frac{2}{21}$ 3. $\frac{4}{5} \cdot \frac{6}{5} = \frac{4 \cdot 6}{5 \cdot 5} = \frac{24}{25}$ 4. $\frac{1}{8} \cdot \frac{7}{9} = \frac{1 \cdot 7}{8 \cdot 9} = \frac{7}{72}$ 5. $\frac{2}{3} \cdot \frac{6}{7} = \frac{2 \cdot 6}{3 \cdot 7} = \frac{12}{21} = \frac{4}{7}$ 6. $\frac{5}{6} \cdot \frac{4}{10} = \frac{5 \cdot 4}{6 \cdot 10} = \frac{20}{60} = \frac{1}{3}$ 7. $\frac{11}{14} \cdot \frac{7}{22} = \frac{11 \cdot 7}{14 \cdot 22} = \frac{1 \cdot 1}{2 \cdot 2} = \frac{1}{4}$ **Столбец 2:** 1. $\frac{4}{5} : \frac{1}{2} = \frac{4}{5} \cdot \frac{2}{1} = \frac{8}{5} = 1\frac{3}{5}$ 2. $\frac{3}{7} : \frac{6}{7} = \frac{3}{7} \cdot \frac{7}{6} = \frac{3}{6} = \frac{1}{2}$ 3. $\frac{1}{2} : \frac{3}{4} = \frac{1}{2} \cdot \frac{4}{3} = \frac{4}{6} = \frac{2}{3}$ 4. $\frac{5}{7} : \frac{5}{7} = 1$ 5. $\frac{8}{11} : \frac{16}{77} = \frac{8}{11} \cdot \frac{77}{16} = \frac{1 \cdot 7}{1 \cdot 2} = \frac{7}{2} = 3\frac{1}{2}$ 6. $\frac{5}{23} : \frac{15}{46} = \frac{5}{23} \cdot \frac{46}{15} = \frac{1 \cdot 2}{1 \cdot 3} = \frac{2}{3}$ 7. $\frac{14}{25} : \frac{21}{50} = \frac{14}{25} \cdot \frac{50}{21} = \frac{2 \cdot 2}{1 \cdot 3} = \frac{4}{3} = 1\frac{1}{3}$ **Столбец 3:** 1. $\frac{5}{7} \cdot \frac{21}{15} : \frac{9}{24} = \frac{5 \cdot 21 \cdot 24}{7 \cdot 15 \cdot 9} = \frac{1 \cdot 3 \cdot 24}{1 \cdot 3 \cdot 9} = \frac{24}{9} = \frac{8}{3} = 2\frac{2}{3}$ 2. $\frac{4}{5} : \frac{8}{10} \cdot \frac{20}{2} = \frac{4}{5} \cdot \frac{10}{8} \cdot \frac{20}{2} = 1 \cdot 10 = 10$ 3. $\frac{6}{7} \cdot \frac{3}{9} \cdot \frac{28}{30} = \frac{6 \cdot 3 \cdot 28}{7 \cdot 9 \cdot 30} = \frac{1 \cdot 1 \cdot 4}{1 \cdot 3 \cdot 5} = \frac{4}{15}$ 4. $\frac{40}{50} : \frac{20}{5} \cdot \frac{3}{4} = \frac{40}{50} \cdot \frac{5}{20} \cdot \frac{3}{4} = \frac{2}{10} \cdot \frac{3}{4} = \frac{6}{40} = \frac{3}{20}$ 5. $\frac{17}{20} \cdot \frac{10}{34} : \frac{5}{2} = \frac{17 \cdot 10 \cdot 2}{20 \cdot 34 \cdot 5} = \frac{1 \cdot 1 \cdot 2}{2 \cdot 2 \cdot 5} = \frac{2}{20} = \frac{1}{10}$ 6. $\frac{15}{20} \cdot \frac{150}{200} : \frac{2}{3} = \frac{3}{4} \cdot \frac{3}{4} \cdot \frac{3}{2} = \frac{27}{32}$ 7. $\frac{14}{63} \cdot \frac{18}{28} \cdot \frac{2}{6} = \frac{14 \cdot 18 \cdot 2}{63 \cdot 28 \cdot 6} = \frac{1 \cdot 3 \cdot 1}{7 \cdot 2 \cdot 3} = \frac{3}{42} = \frac{1}{14}$