(-x/y^2)^2[-(x/y)^2]^-3÷(x^-1y)^4 =(x^2*y^-4)*(x^-3y^6)÷(x^-4y^4) =(x^2*y^-4)*(x^-3y^6)*(x^4y^-4) =x^5/y^2
