[tex]\dfrac{1}{2}=\dfrac{1\cdot5}{2\cdot5}=\dfrac{5}{10}=\dfrac{5\cdot2}{10\cdot2}=\dfrac{10}{20}\\\\\dfrac{2}{5}=\dfrac{2\cdot2}{5\cdot2}=\dfrac{4}{10}=\dfrac{4\cdot2}{10\cdot2}=\dfrac{8}{20}\\\\Answer:\dfrac{1}{2}=\dfrac{10}{20} > \boxed{\dfrac{9}{20}} > \dfrac{8}{20}=\dfrac{2}{5}[/tex]
