In general,
[tex]x^n=x\cdot x\cdot x\cdot\ldots\cdot x\to n\text{ times x}[/tex]
Therefore, in our case,
[tex]\begin{gathered} (\frac{1}{5})^4=\frac{1}{5}\cdot\frac{1}{5}\cdot\frac{1}{5}\cdot\frac{1}{5}=\frac{1}{25}\cdot\frac{1}{25}=\frac{1}{625} \\ \Rightarrow(\frac{1}{5})^4=\frac{1}{625} \end{gathered}[/tex]
Thus, the answer is the second option (top to bottom)
