Answer
{25}
Work Step by Step
For all positive numbers $a$, where $a\ne1$, and all positive numbers $x$, we know that $y=log_{a}x$ means the same as $x=a^{y}$.
Therefore, $log_{x}5=\frac{1}{2}$ means the same as $x^{\frac{1}{2}}=5$.
We know that $x=25$, because $25^{\frac{1}{2}}=\sqrt 25=5$.