[tex]a)2\cdot\frac{1}{3}\cdot\sqrt{3}\sqrt{21}=2\cdot\frac{1}{3}\cdot\sqrt{3}\cdot\sqrt{3}\cdot\sqrt{7}=\\
=2\cdot\frac{1}{3}\cdot{3}\cdot\sqrt{7}=2\sqrt{7}\\
b)\frac{\sqrt{5}}{\sqrt{80}}=\frac{1}{\sqrt{16}}=\frac{1}{4}[/tex]
[tex]c)\frac{\sqrt{75}}{\sqrt{147}}=\frac{\sqrt{25}}{\sqrt{49}}=\frac{5}{7}\\
d)\frac{3\cdot 8\sqrt{5}}{4\cdot 3\sqrt{5}}=2\\
e)\frac{4\cdot \sqrt{7}}{2\sqrt{7}}=2\\
f)\frac{3\sqrt{3}}{4\sqrt{3}}=\frac{3}{4}\\
g)\frac{10\sqrt{7}}{\sqrt{7}}=10[/tex]
