#### Answer

$\dfrac{3x}{y^{2}}\cdot\dfrac{7y}{4x}=\dfrac{21}{4y}$

#### Work Step by Step

$\dfrac{3x}{y^{2}}\cdot\dfrac{7y}{4x}$
Multiply both rational expressions and simplify by removing repeated factors in the numerator and the denominator:
$\dfrac{3x}{y^{2}}\cdot\dfrac{7y}{4x}=\dfrac{(3x)(7y)}{(y^{2})(4x)}=\dfrac{21xy}{4xy^{2}}=\dfrac{21}{4y}$