Answer
5
Work Step by Step
We know that $y=log_{b}x$ is equivalent to $b^{y}=x$ (where $x\gt0$, $b\gt0$, and $b\ne1$).
Therefore, $log_{2}8+log_{5}25=3+2=5$.
We know that $log_{2}8=3$, because $2^{3}=8$. We know that $log_{5}25=2$, because $5^{2}=25$.