Multiply $ \dfrac{6x}{10x-8} $ by $ \dfrac{5x-4}{15x+5} $ to get $ \dfrac{ 6x }{ 30x+10 } $.

Step 1: Factor numerators and denominators.

Step 2: Cancel common factors.

Step 3: Multiply numerators and denominators.

Step 4: Simplify numerator and denominator.

$$ \begin{aligned} \frac{6x}{10x-8} \cdot \frac{5x-4}{15x+5} & \xlongequal{\text{Step 1}} \frac{ 6x }{ 2 \cdot \color{red}{ \left( 5x-4 \right) } } \cdot \frac{ 1 \cdot \color{red}{ \left( 5x-4 \right) } }{ 15x+5 } = \\[1ex] & \xlongequal{\text{Step 2}} \frac{ 6x }{ 2 } \cdot \frac{ 1 }{ 15x+5 } \xlongequal{\text{Step 3}} \frac{ 6x \cdot 1 }{ 2 \cdot \left( 15x+5 \right) } \xlongequal{\text{Step 4}} \frac{ 6x }{ 30x+10 } \end{aligned} $$