2.8*(2 1/3:2.8-1)+2 4/5

\[2{,}8 \cdot \left(2\frac{1}{3}:2{,}8-1\right)+2\frac{4}{5}=\frac{14}{5}\cdot\left(\frac{7}{3}:\frac{14}{5}-1\right)+\frac{14}{5}\]

\[=\frac{14}{5}\cdot\left(\frac{5}{6}-1\right)+\frac{14}{5}=\frac{14}{5}\cdot\left(-\frac{1}{6}\right)+\frac{14}{5}\]

\[=-\frac{7}{15}+\frac{42}{15}=\frac{35}{15}=\frac{7}{3}=2\frac{1}{3}\]

Ответ: \(2\frac{1}{3}\).

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