2) (3,42 − 2 5/8) : 1/50;

\(3.42=\frac{171}{50}\), а \(2\frac58=\frac{21}{8}\). Тогда

\[\frac{171}{50}-\frac{21}{8}=\frac{684-525}{200}=\frac{159}{200}.\]

\[\frac{159}{200}:\frac1{50}=\frac{159}{200}\cdot50=\frac{159}{4}=39\frac34.\]

Ответ: \(39\frac34\).