[tex]\dfrac{4}{10}=\dfrac{4:2}{10:2}=\boxed{\dfrac{2}{5}}\\\\\dfrac{4}{10}=\dfrac{4\cdot2}{10\cdot2}=\boxed{\dfrac{8}{20}}\\\\\dfrac{4}{10}=\dfrac{2}{5}=\dfrac{2\cdot3}{5\cdot3}=\boxed{\dfrac{6}{15}}\\\\\dfrac{4}{10}=\dfrac{2}{5}=\dfrac{2\cdot5}{5\cdot5}=\boxed{\dfrac{10}{25}}\\\\\dfrac{4}{10}=\dfrac{4\cdot5}{10\cdot5}=\boxed{\dfrac{20}{50}}\\\vdots[/tex]