\(18\dfrac{2}{7}.\dfrac{3}{4}-6\dfrac{2}{7}.\dfrac{3}{4}=\dfrac{128}{7}.\dfrac{3}{4}-\dfrac{44}{7}.\dfrac{3}{4}=\left(\dfrac{128}{7}-\dfrac{44}{7}\right).\dfrac{3}{4}=12.\dfrac{3}{4}=9\)
\(18\dfrac{2}{7}\cdot\dfrac{3}{4}-6\dfrac{2}{7}\cdot\dfrac{3}{4}\)
\(=\dfrac{3}{4}\left(18+\dfrac{2}{7}-6-\dfrac{2}{7}\right)\)
\(=12\cdot\dfrac{3}{4}=9\)