| $$ \begin{aligned}4xy+7xy+xy& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}12xy\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{4xy} + \color{red}{7xy} + \color{red}{xy} = \color{red}{12xy} $$ |