The simplified value of $4 \sqrt {12} - \sqrt {50} - 7 \sqrt {48}$ is ________

Question

$\begin{array}{1 1} -5 \sqrt{2}+20 \sqrt 3 \\ 5 \sqrt{2}+20 \sqrt 3 \\-5 \sqrt{2}-20 \sqrt 3\\5 \sqrt{2}-20 \sqrt 3 \end{array}$