\[7\sqrt{3} - 4\sqrt{12} + \sqrt{48} =\]
\[= 7\sqrt{3} - 4\sqrt{4 \cdot 3} + \sqrt{16 \cdot 3} =\]
\[= 7\sqrt{3} - 8\sqrt{3} + 4\sqrt{3} = 3\sqrt{3}\]