\[- 6\frac{4}{9}\ :\left( - 3\frac{1}{3} \right) = \frac{58}{9}\ :\frac{10}{3} = \frac{58}{9} \cdot \frac{3}{10} =\]
\[= \frac{29 \cdot 2 \cdot 3}{3 \cdot 3 \cdot 2 \cdot 5} = \frac{29}{15} = 1\frac{14}{15}\]