8. Найдите значение выражения: 1) (17/25 − 2/15) − 1/10; 2) 7/20 − (11/40 − 3/16); 3) (1/12 + 1/3) + (8/15 − 1/2); 4) (7/8 − 5/6) − (4/9 − 5/12).

1. \(\frac{102}{150}-\frac{20}{150}-\frac{15}{150}=\frac{67}{150}\).
2. \(\frac7{20}-\left(\frac{22}{80}-\frac{15}{80}\right)=\frac{28}{80}-\frac7{80}=\frac{21}{80}\).
3. \(\frac5{12}+\frac1{30}=\frac{25}{60}+\frac2{60}=\frac9{20}\).
4. \(\frac1{24}-\frac1{36}=\frac3{72}-\frac2{72}=\frac1{72}\).

Ответ: 1) \(\frac{67}{150}\); 2) \(\frac{21}{80}\); 3) \(\frac9{20}\); 4) \(\frac1{72}\).