Answer :

12-[20-2(6²/3*2²)]

=12-[20-2(36/3*4)]

=12-[20-2(12*4)]

=12-[20-2(48)]

=12-[20-96]

=12-(-76)

=12+76

=88
[tex]12-\bigg{[}20-2\cdot \bigg{(} \frac{\big{6^2}}{\big{3}} \cdot2^2\bigg{)}\bigg{]}=12-\bigg{[}20-2\cdot \bigg{(} \frac{\big{36}}{\big{3}} \cdot4\bigg{)}\bigg{]}=\\\\=12-(20-2\cdot 12 \cdot4)=12-(20-96)=12-(-76)=12+76=88[/tex]