\(a,\dfrac{2x-1}{3}< \dfrac{x+6}{2}\)
\(\Leftrightarrow\dfrac{4x-2}{6}< \dfrac{3x+18}{6}\)
\(\Leftrightarrow4x-2< 3x+18\)
\(\Leftrightarrow4x-3x< 2+18\)
\(\Leftrightarrow x< 20\)
\(b,\dfrac{5\left(x-1\right)}{6}-1>\dfrac{2\left(x+1\right)}{3}\)
\(\Leftrightarrow\dfrac{5x-11}{6}>\dfrac{4x+4}{6}\)
\(\Leftrightarrow5x-11>4x+4\)
\(\Leftrightarrow5x-4x>11+4\)
\(\Leftrightarrow x>15\)