[tex](\sqrt3-2)(5\sqrt5-x)=3\sqrt3-6\\\\(\sqrt3-2)(5\sqrt5-x)=3(\sqrt3-2)\ \ \ |:(\sqrt3-2)\\\\5\sqrt5-x=3\\\\-x=3-5\sqrt5\ \ \ |:(-1)\\\\x=5\sqrt5-3[/tex]
