| $$ \begin{aligned}3xy+6xy+4xy& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}13xy\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{3xy} + \color{red}{6xy} + \color{red}{4xy} = \color{red}{13xy} $$ |