Answer
$\frac{63y-20x}{36xy}$
Work Step by Step
To simplify this expression, we first need to find the common denominator (the LCM), which is $36xy$. Therefore, we obtain:
$\frac{7}{4x}-\frac{5}{9y}$
=$\frac{7(9y)-5(4x)}{36xy}$
=$\frac{63y-20x}{36xy}$