Задание 1. Найдите значение: 1) 3/4 · 6/5; 2) 21/5 : 3/7; 3) 3/5 · 25/4; 4) 9/5 · 2/3; 5) 5/3 · 9/2; 6) 7/5 · 12/35; 7) 12/5 : 15/2; 8) 6/5 : 4/11; 9) 3/5 : 4/35; 10) 15/4 : 3/7; 11) 21/2 : 3/5; 12) 14/5 : 7/2.

1. \(\frac{3}{4}\cdot\frac{6}{5}=\frac{18}{20}=\frac{9}{10}\).
2. Деление заменяем умножением на обратную дробь: \(\frac{21}{5}:\frac{3}{7}=\frac{21}{5}\cdot\frac{7}{3}=\frac{49}{5}\).
3. \(\frac{3}{5}\cdot\frac{25}{4}=\frac{15}{4}\).
4. \(\frac{9}{5}\cdot\frac{2}{3}=\frac{6}{5}\).
5. \(\frac{5}{3}\cdot\frac{9}{2}=\frac{15}{2}\).
6. \(\frac{7}{5}\cdot\frac{12}{35}=\frac{12}{25}\).
7. \(\frac{12}{5}:\frac{15}{2}=\frac{12}{5}\cdot\frac{2}{15}=\frac{8}{25}\).
8. \(\frac{6}{5}:\frac{4}{11}=\frac{6}{5}\cdot\frac{11}{4}=\frac{33}{10}\).
9. \(\frac{3}{5}:\frac{4}{35}=\frac{3}{5}\cdot\frac{35}{4}=\frac{21}{4}\).
10. \(\frac{15}{4}:\frac{3}{7}=\frac{15}{4}\cdot\frac{7}{3}=\frac{35}{4}\).
11. \(\frac{21}{2}:\frac{3}{5}=\frac{21}{2}\cdot\frac{5}{3}=\frac{35}{2}\).
12. \(\frac{14}{5}:\frac{7}{2}=\frac{14}{5}\cdot\frac{2}{7}=\frac{4}{5}\).

Ответ: 1) \(\frac{9}{10}\); 2) \(\frac{49}{5}\); 3) \(\frac{15}{4}\); 4) \(\frac{6}{5}\); 5) \(\frac{15}{2}\); 6) \(\frac{12}{25}\); 7) \(\frac{8}{25}\); 8) \(\frac{33}{10}\); 9) \(\frac{21}{4}\); 10) \(\frac{35}{4}\); 11) \(\frac{35}{2}\); 12) \(\frac{4}{5}\).