| $$ \begin{aligned}4x-18-5x+17& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-x-1\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{4x} \color{red}{-18} \color{blue}{-5x} + \color{red}{17} = \color{blue}{-x} \color{red}{-1} $$ |