We have two fractions, \dfrac{2}{5} 5 2 ​ start fraction, 2, divided by, 5, end fraction and \dfrac{3}{10} 10 3 ​ start fraction, 3, divided by, 10, end fraction, and we want to rewrite them so that they have a common denominator (and whole number numerators). We have two fractions, \dfrac{2}{5} 5 2 ​ start fraction, 2, divided by, 5, end fraction and \dfrac{3}{10} 10 3 ​ start fraction, 3, divided by, 10, end fraction, and we want to rewrite them so that they have a common denominator (and whole number numerators).