$$ \begin{aligned}\frac{6}{15}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}} \frac{ 6 : \color{orangered}{ 3 } }{ 15 : \color{orangered}{ 3 }} \xlongequal{ } \\[1 em] & \xlongequal{ }\frac{2}{5}\end{aligned} $$ | |
① | Divide both the top and bottom numbers by $ \color{orangered}{ 3 } $. |