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