a) \(\dfrac{17}{2}-\dfrac{31}{6}=\dfrac{51}{6}-\dfrac{31}{6}=\dfrac{51-31}{6}=\dfrac{20}{6}=\dfrac{10}{3}m\)
b) \(\dfrac{20}{3}-\dfrac{17}{6}=\dfrac{40}{6}-\dfrac{17}{6}=\dfrac{40-17}{6}=\dfrac{23}{6}\)
\(=\dfrac{33}{6}-\dfrac{23}{6}=\dfrac{33-23}{6}=\dfrac{10}{6}=\dfrac{5}{3}m\)