\begin{array}{c}\color{#003366}{-Gw}\color{#005A9C}{en}\color{#007ACC}{St}\color{#00AEEF}{ac}\color{#00CFFF}{y}\color{#A4D3EE}{-}\color{#D3D3D3}{}\color{#E0E0E0}{}\end{array} 

`(4x-1)^3 - (4x-3)(16x^2 + 3)`

`= 64x^3 - 48x^2 + 12x - 1 - 64x^3 - 12x + 48x^2 + 9`

`= 64x^3 - 64x^3 - 48x^2 + 48x^2 + 12x - 12x - 1 + 9`

`= (64x^3 - 64x^3) + (48x^2 - 48x^2) + (12x - 12x) - 1 + 9`

`= 0 + 0 + 0 +  8`

`= 8`