Ответ:

  1. \[\frac{5}{9}+\frac{1}{3}=\frac{5}{9}+\frac{3}{9}=\frac{8}{9}.\]
  2. \[3\frac{3}{7}:2\frac{2}{5}=\frac{24}{7}:\frac{12}{5}=\frac{24}{7}\cdot\frac{5}{12}=\frac{10}{7}=1\frac{3}{7}.\]
  3. \[\left(\frac{6}{25}-\frac{1}{5}\right)\cdot\frac{5}{6}=\left(\frac{6}{25}-\frac{5}{25}\right)\cdot\frac{5}{6}=\frac{1}{25}\cdot\frac{5}{6}=\frac{1}{30}.\]

Ответ: а) \(\frac{8}{9}\); б) \(1\frac{3}{7}\); в) \(\frac{1}{30}\).