| $$ \begin{aligned}12a^4b^2-10a^4b^2& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2a^4b^2\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{12a^4b^2} \color{blue}{-10a^4b^2} = \color{blue}{2a^4b^2} $$ |