$$ \begin{aligned}4b(2x+5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}8bx+20b\end{aligned} $$ | |
① | Multiply $ \color{blue}{4b} $ by $ \left( 2x+5\right) $ $$ \color{blue}{4b} \cdot \left( 2x+5\right) = 8bx+20b $$ |