$a)\sqrt{3}\left(\sqrt{12}-2\sqrt{48}-4\sqrt{27}\right)=\sqrt{3}\cdot \sqrt{12}-\sqrt{3}\cdot 2\cdot \sqrt{48}-\sqrt{3}\cdot 4\cdot \sqrt{27}=$

$=\sqrt{3\cdot 12}-2\sqrt{3\cdot 48}-4\sqrt{3\cdot 27}=\sqrt{36}-2\sqrt{144}-4\sqrt{81}=$ $=\sqrt{3\cdot 12}-2\sqrt{3\cdot 48}-4\sqrt{3\cdot 27}=\sqrt{36}-2\sqrt{144}-4\sqrt{81}=$

$=6-2\cdot 12-4\cdot 9=6-24-36=-18-36=-54$

$b)\left(\sqrt{80}+\sqrt{500}-4\sqrt{4500}\right):\sqrt{5}=\sqrt{80}:\sqrt{5}+\sqrt{500}:\sqrt{5}-4\sqrt{4500}:\sqrt{5}=$

$=\sqrt{80:5}+\sqrt{500:5}-4\sqrt{4500:5}=\sqrt{16}+\sqrt{100}-4\cdot \sqrt{900}=4+10-4\cdot 30=$

$=14-120=-106$