Задание 1. Найдите значение выражения: 1) (1/12 − 17/15) · 10/3; 2) (7/15 + 19/30) · 9/11; 3) (3/25 − 2/35) · 14; 4) (1/30 + 7/10) · 6.

1. \[\left(\frac{1}{12}-\frac{17}{15}\right)\cdot\frac{10}{3}=\left(\frac{5-68}{60}\right)\cdot\frac{10}{3}=-\frac{63}{60}\cdot\frac{10}{3}=-\frac{7}{2}.\]
2. \[\left(\frac{7}{15}+\frac{19}{30}\right)\cdot\frac{9}{11}=\frac{14+19}{30}\cdot\frac{9}{11}=\frac{33}{30}\cdot\frac{9}{11}=\frac{9}{10}.\]
3. \[\left(\frac{3}{25}-\frac{2}{35}\right)\cdot14=\frac{21-10}{175}\cdot14=\frac{22}{25}.\]
4. \[\left(\frac{1}{30}+\frac{7}{10}\right)\cdot6=\frac{1+21}{30}\cdot6=\frac{22}{5}.\]

Ответ: 1) \(-\frac{7}{2}\); 2) \(\frac{9}{10}\); 3) \(\frac{22}{25}\); 4) \(\frac{22}{5}\).