Answer
$= \frac{4y^{2}-5x}{xy^{2}}$
Work Step by Step
1) In order to find a common denominator, multiply the first fraction by $y^{2}/y^{2}$ and the second fraction by $x/x$ to obtain a common denominator of $xy^{2}$
2) Subtract
$= \frac{4}{x} - \frac{5}{y^{2}}$
$= \frac{4(y^{2})}{xy^{2}} - \frac{5(x)}{xy^{2}}$
$ = \frac{4y^{2}}{xy^{2}} - \frac{5x}{xy^{2}}$
$= \frac{4y^{2}-5x}{xy^{2}}$
