Answer:
The answer would be 7mn^5 - 2m^6 + 14m^2n^4 - 5m^3n^3 + n^6
Explanation:
In order to find that answer, start by grouping all of the terms by their variable values. Ones that are the same should be combined.
8mn^5 - mn^5 = 7mn^5
2m^6 - 4m^6 = -2m^6
5m^2n^4 + 9m^2n^4 = 14m^2n^4
-m^3n^3 - 4m^3n^3 = -5m^3n^3
n^6 = n^6
Now we simply combine them all to get
7mn^5 - 2m^6 + 14m^2n^4 - 5m^3n^3 + n^6