3. \(5\frac{1}{4}\cdot\left(\frac{3}{5}+2\frac{7}{15}-\frac{1}{2}\right)=\)

\(5\frac{1}{4}=\frac{21}{4}\), \(2\frac{7}{15}=\frac{37}{15}\).

\(\frac{3}{5}+\frac{37}{15}-\frac{1}{2}=\frac{18+74-15}{30}=\frac{77}{30}\).

\(\frac{21}{4}\cdot\frac{77}{30}=\frac{1617}{120}=\frac{539}{40}=13\frac{19}{40}\).

Ответ: \(13\frac{19}{40}\).