\(\dfrac{4}{7}\times\dfrac{5}{10}=\dfrac{4\times5}{7\times16}=\dfrac{5}{7\times4}=\dfrac{5}{28}\)
\(\dfrac{3}{5}:\dfrac{9}{10}=\dfrac{3}{5}\times\dfrac{10}{9}=\dfrac{3\times10}{5\times9}=\dfrac{2}{3}\)
\(2:\dfrac{4}{9}=2\times\dfrac{9}{4}=\dfrac{2\times9}{4}=\dfrac{9}{2}\)
\(\dfrac{2}{3}:2=\dfrac{2}{3}\times\dfrac{1}{2}=\dfrac{1}{3}\)
#Toru