[(m-n)^2*(n-m)^3]^2/(m-n)^4
=[(m-n)^2*(m-n)^6]/(m-n)^4
=(m-n)^(2+6-4)
=(m-n)^4
[(-x^5)^2]^3/[(x^4)^2/(x^2)^3]
=x^30/[x^(8-6)
=x^(30-2)
=x^28