[tex]1m=100cm\to1cm=\dfrac{1}{100}m\\\\1dam=10m\\\\\text{therefore}\\\\\dfrac{2}{5}cm=\dfrac{2}{5}\cdot\dfrac{1}{100}m=\dfrac{1}{250}m\\\\\dfrac{1}{3}dam=\dfrac{1}{3}\cdot10m=\dfrac{10}{3}m\\\\\dfrac{2}{5}cm\times\dfrac{1}{3}dam=\dfrac{1}{250}m\times\dfrac{10}{3}m=\dfrac{1}{75}m^2[/tex]
