[ (10)(x^3)(y^2) / (5)(x^-3)(y^4) ]^-3
[ (2)(x^3)(y^2) / (x^-3)(y^4) ]^-3
[ (2)(x^6)(y^2) / (y^4) }^-3
[ (2)(x^6)(y^-2) ]^-3
(2^-3)(x^-18)(y^6)
---Not simplified (contains negative exponents)
(1/8)(x^-18)(y^6)
---Fully simplified
(y^6) / (8)(x^18)
Hope this helps!