$B=(1-2.2\sqrt3.1+12)(3+2.2\sqrt3.1+4)- 8\sqrt{20+2\sqrt{43+24\sqrt3}}$
$=(1-2\sqrt3)^2.(2+\sqrt3)^2-8\sqrt{20+2\sqrt{(3\sqrt3+4)^2}}$
$=(1-2\sqrt3)^2.(2+\sqrt3)^2-8\sqrt{20+2(3\sqrt3+4)}$
$=(1-2\sqrt3)^2.(2+\sqrt3)^2-8\sqrt{28+6\sqrt3}$
$=(1-2\sqrt3)^2.(2+\sqrt3)^2-8\sqrt{(3\sqrt3+1)^2}$
$=(1-2\sqrt3)^2.(2+\sqrt3)^2-8.(3\sqrt3+1)$
$=[(1-2\sqrt3)(2+\sqrt3)]^2-8(3\sqrt3+1)$
$=(2+\sqrt3-4\sqrt3-6)^2-8(3\sqrt3+1)$
$=(-3\sqrt3-4)^2-8(3\sqrt3+1)$
$=27+24\sqrt3+16-24\sqrt3-8$
$=35$
