Simplify $\left(\left(\frac{5}{2}\right)^{\left(\left(\frac{10.5}{4}\right)^5\right)}\right)^{-2}$ using the power of a power property: $\left(a^m\right)^n=a^{m\cdot n}$. In the expression, $m$ equals $\left(\frac{10.5}{4}\right)^5$ and $n$ equals $-2$