Lim of x->25 coming from the left (square root of x )- 5/(x-25)
Re brackets: (sqrt x)- 5/(x- 25) would normally be intepreted (by myself, anyway) as
$\displaystyle \sqrt{x}- \frac{5}{x- 25}$.
By the way, while mr. fantastic's "$\displaystyle t= \sqrt{x}$" substitution is probably simplest you could also think of $\displaystyle x- 25$ as a "difference of squares", $\displaystyle (\sqrt{x})^2- 5^2$ so the problem becomes
$\displaystyle \lim_{x\to 25}\frac{\sqrt{x- 5}}{(\sqrt{x+ 5})(\sqrt{x- 5})}$