#### Answer

The solution is $12$.

#### Work Step by Step

The given equation can be written as:
$$(p^2)^2-p^2-20=0$$
Use the Zero Factor Property by equating each factor to zero, then solve each equation to obtain:
\begin{array}{ccc}
\\&x-12=0 &\text{or} &x-3=0
\\&x=12 &\text{or} &x=3
\end{array}
Note that $3$ does not satisfy the original equation so it is not a solution.
Therefore, the solution is $12$.