To use the Power Rule of Exponents on the expression \((15^6)^2\), we apply the rule that states \((a^m)^n = a^{m \cdot n}\).
Here, \(a = 15\), \(m = 6\), and \(n = 2\):
\[ (15^6)^2 = 15^{6 \cdot 2} = 15^{12} \]
So the equivalent expression is:
15 superscript 12 baseline.