\[8\sqrt{3} - 5\sqrt{12} + 4\sqrt{75} =\]
\[= 8\sqrt{3} - 5\sqrt{4 \cdot 3} + 4\sqrt{25 \cdot 3} =\]
\[= 8\sqrt{3} - 5 \cdot 2\sqrt{3} + 4 \cdot 5\sqrt{3} =\]
\[= 8\sqrt{3} - 10\sqrt{3} + 20\sqrt{3} = 18\sqrt{3}\]