№ 2. Вычислите наиболее удобным способом: А) 4(2/3 + 1/3 − 9/6); Б) 13/15 − 3/4 + 2 · 2/5; В) 2 3/4 + (3/5 − 3/10) · 1/4; Г) (2,125 · 15/17 − 1 7/12) : 7,25; Д) (7,42 : 5/9 − (−1,48) : 1 4/5) : 0,35; Е) (0,919 − 2/7) − (7,81 : 1,3) : 0,04; Ж) (0,014 + 2/3 · 0,286) : (−0,4) : (−0,025).

А) \(4\left(\frac{2}{3}+\frac{1}{3}-\frac{9}{6}\right)=4\left(1-\frac{3}{2}\right)=4\cdot\left(-\frac{1}{2}\right)=-2\).

Б) \(\frac{13}{15}-\frac{3}{4}+2\cdot\frac{2}{5}=\frac{52}{60}-\frac{45}{60}+\frac{48}{60}=\frac{55}{60}=\frac{11}{12}\).

В) \(2\frac{3}{4}+\left(\frac{3}{5}-\frac{3}{10}\right)\cdot\frac{1}{4}=\frac{11}{4}+\frac{3}{10}\cdot\frac{1}{4}=\frac{11}{4}+\frac{3}{40}=\frac{113}{40}=2\frac{33}{40}\).

Г) \(\left(2,125\cdot\frac{15}{17}-1\frac{7}{12}\right):7,25=\left(\frac{17}{8}\cdot\frac{15}{17}-\frac{19}{12}\right):\frac{29}{4}=\left(\frac{15}{8}-\frac{19}{12}\right)\cdot\frac{4}{29}=\frac{7}{24}\cdot\frac{4}{29}=\frac{7}{174}\).

Д) \(\left(7,42:\frac{5}{9}-(-1,48):1\frac{4}{5}\right):0,35=\left(\frac{371}{50}\cdot\frac{9}{5}+\frac{37}{25}\cdot\frac{5}{9}\right):\frac{7}{20}=\frac{31901}{787}\).

Е) \((0,919-\frac{2}{7})-(7,81:1,3):0,04=\frac{4433}{7000}-\frac{781}{130}\cdot25=-\frac{13609871}{91000}\).

Ж) \((0,014+\frac{2}{3}\cdot0,286):(-0,4):(-0,025)=\left(\frac{7}{500}+\frac{2}{3}\cdot\frac{143}{500}\right):\left(-\frac{2}{5}\right):\left(-\frac{1}{40}\right)=\frac{307}{15}=20\frac{7}{15}\).

Ответ: А) −2; Б) \(\frac{11}{12}\); В) \(2\frac{33}{40}\); Г) \(\frac{7}{174}\); Д) \(\frac{31901}{787}\); Е) \(-\frac{13609871}{91000}\); Ж) \(20\frac{7}{15}\).