4. Выполните умножение дробей: a) 2/3 * 5/7 b) 3/5 * 5/11 c) 2/9 * 7/11 d) 4/5 * 6/19 e) 2/5 * 18/9 f) 5/6 * 2/15 g) 7/8 * 12/9 h) 6/25 * 15/17 i) 1/2 * 3/10 j) 10 * 5/7 k) 7 * 3/4 l) 3 * 2/10

a) \( \frac{2}{3} \cdot \frac{5}{7} = \frac{2 \cdot 5}{3 \cdot 7} = \frac{10}{21} \) b) \( \frac{3}{5} \cdot \frac{5}{11} = \frac{3 \cdot 5}{5 \cdot 11} = \frac{15}{55} = \frac{3}{11} \) c) \( \frac{2}{9} \cdot \frac{7}{11} = \frac{2 \cdot 7}{9 \cdot 11} = \frac{14}{99} \) d) \( \frac{4}{5} \cdot \frac{6}{19} = \frac{4 \cdot 6}{5 \cdot 19} = \frac{24}{95} \) e) \( \frac{2}{5} \cdot \frac{18}{9} = \frac{2 \cdot 18}{5 \cdot 9} = \frac{36}{45} = \frac{4}{5} \) f) \( \frac{5}{6} \cdot \frac{2}{15} = \frac{5 \cdot 2}{6 \cdot 15} = \frac{10}{90} = \frac{1}{9} \) g) \( \frac{7}{8} \cdot \frac{12}{9} = \frac{7 \cdot 12}{8 \cdot 9} = \frac{84}{72} = \frac{7}{6} = 1 \frac{1}{6} \) h) \( \frac{6}{25} \cdot \frac{15}{17} = \frac{6 \cdot 15}{25 \cdot 17} = \frac{90}{425} = \frac{18}{85} \) i) \( \frac{1}{2} \cdot 12 \frac{3}{10} = \frac{1 \cdot 3}{2 \cdot 10} = \frac{3}{20} \) j) \( \frac{10 \cdot 5}{7} = \frac{50}{7} = 7 \frac{1}{7} \) k) \( \frac{7 \cdot 3}{4} = \frac{21}{4} = 5 \frac{1}{4} \) l) \( \frac{3 \cdot 2}{10} = \frac{6}{10} = \frac{3}{5} \) Ответы: a) 10/21 b) 3/11 c) 14/99 d) 24/95 e) 4/5 f) 1/9 g) 1 1/6 h) 18/85 i) 3/20 j) 7 1/7 k) 5 1/4 l) 3/5