\(25^{2x}:5^x=125^2\)
\(\Rightarrow5^{4x}:5^x=\left(5^3\right)^2\)
\(\Rightarrow5^{4x-x}=5^6\)
\(\Rightarrow5^{3x}=5^6\)
\(\Rightarrow3x=6\)
\(\Rightarrow x=2\)
\(=\left(25^2\right)^x\div5x=125^2\)
\(=625^x\div5^x=125^2\)
\(=\left(625\div5\right)^x=125^2\)
\(=125^x=125^2\)
\(=>x=2\)