[tex]\begin{gathered} \text{If two lines are parallel, then the both lines will have same slope.} \\ \text{the slope from the first equation.} \\ -2x-3y=8 \\ 3y=-2x-8 \\ y=\frac{-2}{3}x-\frac{8}{3} \\ \text{Slope }\Rightarrow m=-\frac{2}{3} \\ \text{Now, from the second equation.} \\ 4x-2ay=9 \\ 2ay=4x-9 \\ y=\frac{4}{2a}x-\frac{9}{2a} \\ \text{Slope from this equation is} \\ m=\frac{4}{2a}=\frac{2}{a} \\ \text{equate both slope } \\ \frac{2}{a}=-\frac{2}{3} \\ a=-3 \end{gathered}[/tex]
