Answer
$x=2$
Work Step by Step
If $b\gt0$ and $b\ne1$, then $y=log_{b}x$ means $x=b^{y}$ for every $x$ and every real number $y$.
Therefore, $log_{x}8=3$ is equivalent to $x^{3}=8$.
We can now solve for x. Take the cube root of both sides.
$(x^{3})^{\frac{1}{3}}=(8)^{\frac{1}{3}}$
$x=2$