\[4a^{\backslash 2a - 3} - \frac{8a^{2}}{2a - 3} =\]
\[= \frac{8a^{2} - 12a - 8a^{2}}{2a - 3} =\]
\[= - \frac{12a}{2a - 3} = \frac{12a}{3 - 2a}\text{.\ }\]