\[\frac{5x - 10}{2x + 3}\ :\frac{x^{2} - 4}{4x + 6} =\]
\[= \frac{5 \cdot (x - 2) \cdot 2 \cdot (2x + 3)}{(2x + 3)(x - 2)(x + 2)} = \frac{10}{x + 2}\]