Answer:
[tex] {25}^{x} = {5}^{4} \\ {( {5}^{2}) }^{x} = {5}^{4} \\ {5}^{2x} = {5}^{4} \\ 2x = 4 \\ x = \frac{4}{2} \\ \boxed{x = 2}[/tex]