ПОМОГИТЕ!!!!!!!!!!!!!

Решите задачу:

$(\sqrt{2\frac{4}{7}}-\sqrt{7\frac{1}{7}}):\sqrt{\frac{2}{63}}=$

$=(\sqrt{\frac{18}{7}}-\sqrt{\frac{50}{7}})*\sqrt{\frac{63}{2}}=$

$=\sqrt{\frac{18}{7}}*\sqrt{\frac{63}{2}} -\sqrt{\frac{50}{7}}*\sqrt{\frac{63}{2}}=$

$=\sqrt{\frac{18}{7}*{\frac{63}{2}}} -\sqrt{\frac{50}{7}*{\frac{63}{2}}=$

$=\sqrt{\frac{18}{2}*{\frac{63}{7}}} -\sqrt{\frac{50}{2}*{\frac{63}{7}}=$

$=\sqrt{9*9} -\sqrt{25*9}=9-5*3=9-15=-6$