[tex]\left\| \begin{array}{ll} 6x-4a=0 \\ 2x-8 = 16 \end{array} \right \Rightarrow \left\| \begin{array}{ll} 6x-4a=0 \\ 2x-8-16=0 \end{array} \right \Rightarrow \left\| \begin{array}{ll} 6x-4a=0 \\ 2x-24=0\Big|\cdot 3 \end{array} \right \Rightarrow \\ \\ \Rightarrow \left\| \begin{array}{ll} 6x-4a=0 \\ 6x-72 = 0\end{array} \right|\Rightarrow 4a = 72 \Rightarrow a = \dfrac{72}{4} \Rightarrow \boxed{a = 18 }[/tex]
