Step-by-step explanation:
[tex](16 + 2x)(12 + 2x) [/tex]
[tex] = 4x^{2} + 24x + 32x + 192 = 396[/tex]
[tex]4x^{2} + 56x - 204[/tex]
this then becomes the answer of
[tex]4(x + 17) \times (x - 3)[/tex]