\(\left(6\frac{1}{3}-4\frac{5}{9}\right)\cdot\left(\frac{3}{7}+2\frac{1}{21}\right)\)

\(6\frac{1}{3}-4\frac{5}{9}=\frac{16}{9}\), а \(\frac{3}{7}+2\frac{1}{21}=\frac{52}{21}\).

\(\frac{16}{9}\cdot\frac{52}{21}=\frac{832}{189}=4\frac{76}{189}\).

Ответ: \(4\frac{76}{189}\).