Multiplicación de fracciones: Completar los números faltantes

$\frac{1}{2}\times?=\frac{1}{4}$

$\frac{1}{2}$$$$$

$\frac{2}{4}\times?=\frac{2}{7}$

$\frac{4}{7}$

$\frac{3}{5}\times?=\frac{2}{4}$

$\frac{5}{6}$

$\frac{5}{6}\times?=\frac{1}{3}$

$\frac{2}{5}$

$\frac{1}{4}\times?=\frac{1}{5}$

$\frac{4}{5}$

$\frac{5}{7}\times?=\frac{1}{3}$

$\frac{7}{15}$

$\frac{2}{3}\times?=\frac{1}{3}$

$\frac{1}{2}$

$\frac{2}{3}\times?=\frac{1}{6}$

$\frac{1}{4}$

$\frac{3}{4}\times?=\frac{1}{5}$

$\frac{4}{15}$

$\frac{2}{3}\times?=\frac{1}{4}$

$\frac{3}{8}$