Answer
$ x=\displaystyle \frac{2}{3}$
Work Step by Step
$ 125^{x}=25\qquad $ ... recognize $125$ and $25$ as powers of $5$
$(5^{3})^{x} =5^{2}\qquad $ ... apply: $(a^{m})^{n}=a^{mn}$
$5^{3x}=5^{2}\qquad $... If $ b^{M}=b^{N}$, then $ M=N $
$3x=2\qquad $...$/\div 3$
$ x=\displaystyle \frac{2}{3}$
