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

Решение:

1. \[ \left( \frac{1}{12} - \frac{17}{15} \right) \times \frac{10}{3} = \left( \frac{1 \times 5}{12 \times 5} - \frac{17 \times 4}{15 \times 4} \right) \times \frac{10}{3} = \left( \frac{5}{60} - \frac{68}{60} \right) \times \frac{10}{3} = \frac{-63}{60} \times \frac{10}{3} = \frac{-21}{6} \times \frac{1}{1} = \frac{-7}{2} = -3.5 \]
2. \[ \left( \frac{7}{15} + \frac{19}{30} \right) \times \frac{9}{11} = \left( \frac{7 \times 2}{15 \times 2} + \frac{19}{30} \right) \times \frac{9}{11} = \left( \frac{14}{30} + \frac{19}{30} \right) \times \frac{9}{11} = \frac{33}{30} \times \frac{9}{11} = \frac{3}{30} \times 9 = \frac{1}{10} \times 9 = \frac{9}{10} = 0.9 \]
3. \[ \left( \frac{3}{25} - \frac{2}{35} \right) \times 14 = \left( \frac{3 \times 7}{25 \times 7} - \frac{2 \times 5}{35 \times 5} \right) \times 14 = \left( \frac{21}{175} - \frac{10}{175} \right) \times 14 = \frac{11}{175} \times 14 = \frac{11}{25} \times 2 = \frac{22}{25} = 0.88 \]
4. \[ \left( \frac{1}{30} + \frac{7}{10} \right) \times 6 = \left( \frac{1}{30} + \frac{7 \times 3}{10 \times 3} \right) \times 6 = \left( \frac{1}{30} + \frac{21}{30} \right) \times 6 = \frac{22}{30} \times 6 = \frac{22}{5} = 4.4 \]

Ответ: 1) -3.5; 2) 0.9; 3) 0.88; 4) 4.4