\(\dfrac{5}{2}-\dfrac{11}{12}+\dfrac{9}{14}\)
\(=\dfrac{5\cdot42}{2\cdot42}-\dfrac{11\cdot7}{12\cdot7}+\dfrac{9\cdot6}{14\cdot6}\)
\(=\dfrac{210}{84}-\dfrac{77}{84}+\dfrac{54}{84}\)
\(=\dfrac{210-77+54}{84}\)
\(=\dfrac{187}{84}\)
\(\dfrac{5}{2}-\dfrac{11}{12}+\dfrac{9}{14}\text{=}\dfrac{210}{84}-\dfrac{77}{84}+\dfrac{54}{84}\text{=}\dfrac{210-77+54}{84}\text{=}\dfrac{187}{84}\)