Obliczenia :
[tex]a] \ \sqrt{27}+2\sqrt3=\sqrt{9\cdot3}+2\sqrt3=3\sqrt3+2\sqrt3=\boxed{5\sqrt3}\\\\b] \ \frac{\sqrt{45}-\sqrt{20}}{\sqrt5}=\frac{\sqrt{9\cdot5}-\sqrt{4\cdot5}}{\sqrt5}=\frac{3\sqrt5-2\sqrt5}{\sqrt5}=\frac{\sqrt5}{\sqrt5}=\boxed1[/tex]
