| $$ \begin{aligned}2x-3y+2x-3y& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4x-6y\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{2x} \color{red}{-3y} + \color{blue}{2x} \color{red}{-3y} = \color{blue}{4x} \color{red}{-6y} $$ |