Hey getting stuck on this one

Use definition of the derivative to determine $\displaystyle f'(x)$ where $\displaystyle f(x)= \sqrt{3x}$

$\displaystyle \lim_{h\rightarrow 0} \frac{f(x+h) - f(x)}{h}$

$\displaystyle \lim_{h\rightarrow 0} \frac{\sqrt{3x+3h}-\sqrt{3h}}{h}$

what do i do now?

thanks