Блок 3. Вычислите: 1) (9/10 − 7/15) · 3; 2) (3/4 − 1/6) · 3; 3) (2 1/4 − 1 3/19) · 19; 4) (1/13 − 2 3/4) · 26; 5) (1/5 + 8/15) · 6; 6) (5/22 − 8/11) · 11/5; 7) (9/17 − 11/34) · 17/2; 8) (17/15 − 1/12) · 20/3; 9) (10/13 + 15/4) · 26/5; 10) (5/26 − 3/25) · 13/2.

Сначала выполняем действия в скобках, приводя дроби к общему знаменателю, затем умножаем.

1. \((\frac{9}{10}-\frac{7}{15})\cdot3=\frac{13}{30}\cdot3=\frac{13}{10}\).
2. \((\frac{3}{4}-\frac{1}{6})\cdot3=\frac{7}{12}\cdot3=\frac{7}{4}\).
3. \((2\frac{1}{4}-1\frac{3}{19})\cdot19=(\frac{9}{4}-\frac{22}{19})\cdot19=\frac{83}{76}\cdot19=\frac{83}{4}\).
4. \((\frac{1}{13}-2\frac{3}{4})\cdot26=(\frac{4}{52}-\frac{143}{52})\cdot26=-\frac{139}{2}\).
5. \((\frac{1}{5}+\frac{8}{15})\cdot6=\frac{11}{15}\cdot6=\frac{22}{5}\).
6. \((\frac{5}{22}-\frac{8}{11})\cdot\frac{11}{5}=-\frac{1}{2}\cdot\frac{11}{5}=-\frac{11}{10}\).
7. \((\frac{9}{17}-\frac{11}{34})\cdot\frac{17}{2}=\frac{7}{34}\cdot\frac{17}{2}=\frac{7}{4}\).
8. \((\frac{17}{15}-\frac{1}{12})\cdot\frac{20}{3}=\frac{21}{20}\cdot\frac{20}{3}=7\).
9. \((\frac{10}{13}+\frac{15}{4})\cdot\frac{26}{5}=\frac{235}{52}\cdot\frac{26}{5}=\frac{47}{2}\).
10. \((\frac{5}{26}-\frac{3}{25})\cdot\frac{13}{2}=\frac{47}{650}\cdot\frac{13}{2}=\frac{47}{100}\).