2) [m]\frac{\sqrt{200}+\sqrt{300}}{\sqrt{10} + \sqrt{15}} = \frac{10\sqrt{2}+10\sqrt{3}}{\sqrt{5} \cdot \sqrt{2} + \sqrt{5} \cdot \sqrt{3}} =\frac{10(\sqrt{2}+\sqrt{3})}{\sqrt{5}(\sqrt{2} + \sqrt{3})} = \frac{10}{\sqrt{5}} =\frac{10\sqrt{5}}{5} =2\sqrt{5}[/m]