| $$ \begin{aligned}2(b-3)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}2b-6\end{aligned} $$ | |
| ① | Multiply $ \color{blue}{2} $ by $ \left( b-3\right) $ $$ \color{blue}{2} \cdot \left( b-3\right) = 2b-6 $$ |