$\left(16a{x}^2-24a^{2}x+8ax\right):4=16a{x}^2:4-24a^{2}x:4+8ax:4=4a{x}^2-6a^2+2ax=ax\left(4x-6a+2\right)=2ax\left(2x-3a+1\right)=4ax(\left(x-\frac{3}{2}a+\frac{1}{2}\right)$