#### Answer

$y^{\frac{1}{4}}$

#### Work Step by Step

Let the missing term be $x$
The given expression becomes,
$\frac{x}{y^{\frac{-3}{4}}}= y^{\frac{4}{4}}$
$x=y^{\frac{-3}{4}} \times y^{\frac{4}{4}}$
Using product rule for exponents, $a^{m} \times a^{n} = a^{m+n}$
$x=y^{\frac{-3}{4} + \frac{4}{4} } $
$x=y^{\frac{-3+4}{4} } $
$x=y^{\frac{1}{4} } $