$$ \begin{aligned}9p^2-5p^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4p^2\end{aligned} $$ | |
① | Combine like terms: $$ \color{blue}{9p^2} \color{blue}{-5p^2} = \color{blue}{4p^2} $$ |