Answer
$-7n^3+9$
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.
$=\dfrac{-28n^5}{4n^2} + \dfrac{36n^2}{4n^2}
\\=-7n^{5-2} + 9n^{2-2}
\\=-7n^3+9n^0
\\=-7n^3+9(1)
\\=-7n^3+9$
