| $$ \begin{aligned}4-i-5+4i& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}3i-1\end{aligned} $$ | |
| ① | Combine like terms: $$ \color{blue}{4} \color{red}{-i} \color{blue}{-5} + \color{red}{4i} = \color{red}{3i} \color{blue}{-1} $$ |