How do I simplify $\frac{\sqrt{21}-5}{2} + \frac{2}{\sqrt{21} - 5}$? 
How do I simplify the following equation?
$$\frac{\sqrt{21}-5}{2} + \frac{2}{\sqrt{21} - 5}$$

I have no idea where to start. If I multiply either fraction by its denominator I will still end up with a square root. I know the end result should be $-5$.

$$\frac{\sqrt{21}-5}2+\frac2{\sqrt{21}-5}=\frac{50-10\sqrt{21}}{2\sqrt{21}-10}=-5\frac{\sqrt{21}-5}{\sqrt{21}-5}$$
