# Surds question grade 9 Simplify: (6)/(sqrt(28))-(9)/(sqrt(63))

I am a student and I need help answering this question.
Simplify:
$\frac{6}{\sqrt{28}}$-$\frac{9}{\sqrt{63}}$
What I did:
$\frac{6}{\sqrt{28}}$-$\frac{9}{\sqrt{63}}$
=$\frac{6}{\sqrt{7×4}}$ - $\frac{9}{\sqrt{7×4}}$
= $\frac{6}{2\sqrt{7}}$ - $\frac{9}{3\sqrt{7}}$
$\frac{6}{2\sqrt{7}}$ × $\frac{2\sqrt{7}}{2\sqrt{7}}$ = $\frac{12\sqrt{7}}{14}$
$\frac{9}{3\sqrt{7}}$ × $\frac{3\sqrt{7}}{3\sqrt{7}}$ = $\frac{27\sqrt{7}}{63}$
($\frac{12\sqrt{7}}{14}$)/2 = $\frac{6\sqrt{7}}{7}$
($\frac{27\sqrt{7}}{63}$) /2 = $\frac{3\sqrt{7}}{7}$
$\frac{6\sqrt{7}}{7}$ - $\frac{3\sqrt{7}}{7}$
= $\frac{3\sqrt{7}}{7}$
Thankyou and help is appreciated.
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Hint: $\frac{6}{\sqrt{28}}=\frac{3}{\sqrt{7}}=\frac{9}{\sqrt{63}}$
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Lisantiom
Simply note that
$\frac{6}{\sqrt{28}}-\frac{9}{\sqrt{63}}=\frac{6}{2\sqrt{7}}-\frac{9}{3\sqrt{7}}=\frac{3}{\sqrt{7}}-\frac{3}{\sqrt{7}}=0$