Вычислить: а) 2 1/7 · (2 1/3 + 2 2/15) − 8,8; б) (2 2/3 · 3/8 − 0,12 · 1/2) : 0,4.

а)

\(2\frac{1}{7}=\frac{15}{7}\), \(2\frac{1}{3}=\frac{7}{3}\), \(2\frac{2}{15}=\frac{32}{15}\), \(8,8=\frac{44}{5}\).

\[\frac{15}{7}\cdot\left(\frac{7}{3}+\frac{32}{15}\right)-\frac{44}{5}=\frac{15}{7}\cdot\frac{67}{15}-\frac{44}{5}=\frac{67}{7}-\frac{44}{5}=\frac{335-308}{35}=\frac{27}{35}.\]

б)

\(2\frac{2}{3}=\frac{8}{3}\), \(0,12=\frac{12}{100}\), \(0,4=\frac{4}{10}\).

\[\left(\frac{8}{3}\cdot\frac{3}{8}-0,12\cdot\frac{1}{2}\right):0,4=(1-0,06):0,4=0,94:0,4=2,35.\]

Ответ: а) \(\frac{27}{35}\); б) 2,35.