Answer
$-3xy+5y$
Work Step by Step
Recall the following rule: $\frac{a^{m}}{a^{n}}=a^{m-n}$
In order to solve this problem, use the rule above and cancel out common factors that are in both the numerator and the denominator of the fraction.
$=\dfrac{27x^2y^4}{-9xy^3} - \dfrac{45xy^4}{-9xy^3}
\\=-3x^{2-1}y^{4-3}+ 5x^{1-1}y^{4-3}
\\=-3xy+5x^0y
\\=-3xy+5(1)y
\\=-3xy+5y$
