Hi, do any of you know how to solve this problem?

Find the only value of x in $\displaystyle (-\frac{\pi}{2},0)$ that satisfies the equation

$\displaystyle \frac{\sqrt{3}}{\sin x} + \frac{1}{\cos x} = 4$

The answer was $\displaystyle -\frac{4\pi}{9}$, but I don't know how it came to that answer.

Thanks!