what is the derivative of f(x)= ((f(x)-sqrt(x))/5)

$$\\f(x)=\frac{f(x)-\sqrt x}{5}\\\\
5f(x)=f(x)-\sqrt x\\\\
4f(x)=-\sqrt x\\\\
f(x)=\dfrac{-x^{0.5}}{4}\\\\
f'(x)=\dfrac{-0.5x^{-0.5}}{4}\\\\
f'(x)=\dfrac{-0.5}{4\sqrt{x}}\\\\
f'(x)=\dfrac{-1}{8\sqrt{x}}\\\\$$

I think that is what you wanted.  

Nice one, Melody.....!!!

Thanks Chris.