| $$ \begin{aligned}3x+12y+3x+4y& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}6x+16y\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{3x} + \color{red}{12y} + \color{blue}{3x} + \color{red}{4y} = \color{blue}{6x} + \color{red}{16y} $$ |