Tính:

\(\frac{{{x^2} - {y^2}}}{{6{x^2}y}}:\frac{{x + y}}{{3xy}}\);

\(\frac{{{x^2} - {y^2}}}{{6{x^2}y}}:\frac{{x + y}}{{3xy}} = \frac{{\left( {x - y} \right)\left( {x + y} \right)}}{{6{x^2}y}}.\frac{{3xy}}{{x + y}}\)

\( = \frac{{\left( {x - y} \right)\left( {x + y} \right).3xy}}{{6{x^2}y.\left( {x + y} \right)}} = \frac{{x - y}}{{2x}}\).