| $$ \begin{aligned}12a\frac{b^2}{15a^2}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}\frac{12ab^2}{15a^2}\end{aligned} $$ | |
| ① | Multiply $12a$ by $ \dfrac{b^2}{15a^2} $ to get $ \dfrac{ 12ab^2 }{ 15a^2 } $. Step 1: Write $ 12a $ as a fraction by putting $ \color{red}{1} $ in the denominator. Step 2: Multiply numerators and denominators. Step 3: Simplify numerator and denominator. $$ \begin{aligned} 12a \cdot \frac{b^2}{15a^2} & \xlongequal{\text{Step 1}} \frac{12a}{\color{red}{1}} \cdot \frac{b^2}{15a^2} \xlongequal{\text{Step 2}} \frac{ 12a \cdot b^2 }{ 1 \cdot 15a^2 } = \\[1ex] & \xlongequal{\text{Step 3}} \frac{ 12ab^2 }{ 15a^2 } \end{aligned} $$ |