\[\frac{c + d}{3 - 2c}\ :\frac{c^{2} + 2cd + d^{2}}{2c^{2} - 3c} =\]
\[= \frac{(c + d)c(2c - 3)}{(3 - 2c)\left( c^{2} + 2cd + d^{2} \right)} =\]
\[= \frac{(c + d) \cdot c(2c - 3)}{- (2c - 3)(c + d)^{2}} = - \frac{c}{c + d}.\]