\[- 5\ :\left( - 1\frac{2}{3} \right) = 5\ :\frac{3 + 2}{3} =\]
\[= 5\ :\frac{5}{3} = \frac{5}{1} \cdot \frac{3}{5} = \frac{5 \cdot 3}{5} = 3\]