[tex]\dfrac{8}{15} :\dfrac{3}{20} =\dfrac{8}{\not15^3} *\dfrac{\not20^4}{3} =\dfrac{32}{9}=\boxed{3\dfrac{5}{9} }[/tex]
[tex]\dfrac{1}{9} :\dfrac{5}{12} =\dfrac{1}{\not9^3} *\dfrac{\not12^4}{5} =\boxed{\dfrac{4}{15}}[/tex]
[tex]\dfrac{2}{9} :\dfrac{7}{3} =\dfrac{2}{\not9^3} *\dfrac{\not3^1}{7} =\boxed{\dfrac{2}{21} }[/tex]
