Mínimo común denominador: Encontrando un denominador común multiplicando los denominadores

$\frac{1}{4}+\frac{1}{9}=$

$\frac{13}{36}$

$\frac{1}{7}+\frac{1}{3}=$

$\frac{10}{21}$

$\frac{2}{5}+\frac{1}{6}=$

$\frac{17}{30}$

$\frac{3}{8}+\frac{2}{3}=$

$\frac{25}{24}$

$\frac{1}{2}+\frac{2}{9}=$

$\frac{13}{18}$

$\frac{2}{10}+\frac{1}{3}=$

$\frac{16}{30}$

$\frac{1}{5}+\frac{1}{3}=$

$\frac{8}{15}$

$\frac{1}{4}+\frac{4}{9}=$

$\frac{25}{36}$

$\frac{2}{5}+\frac{3}{6}=$

$\frac{27}{30}$

$\frac{2}{8}+\frac{2}{3}=$

$\frac{22}{24}$

$\frac{1}{2}+\frac{2}{9}=$

$\frac{13}{18}$

$\frac{1}{4}+\frac{2}{6}=$

$\frac{7}{12}$

$\frac{2}{5}+\frac{1}{3}=$

$\frac{11}{15}$

$\frac{2}{5}+\frac{1}{4}=$

$\frac{13}{20}$

$\frac{1}{2}+\frac{1}{5}=$

$\frac{7}{10}$

$\frac{2}{6}+\frac{3}{7}=$

$\frac{32}{42}$

$\frac{2}{5}+\frac{1}{3}=$

$\frac{11}{15}$