To divide polynomials by a monomial written in standard form, you can divide each term of the polynomial by the monomial separately. Applying this to the given expression, we get:
(30c^8d^3 - 3bc^6d^2 + 6c^8d) / (12c^2d)
= 30c^8d^3/(12c^2d) - 3bc^6d^2/(12c^2d) + 6c^8d/(12c^2d)
= 2.5c^(8-2)d^(3-1) - 0.25bc^(6-2)d^(2-1) + 0.5c^(8-2)d^(1-1)
= 2.5c^6d^2 - 0.25bc^4d + 0.5c^6
= 5c^6d^2 - 0.5bc^4d + c^6/2
Therefore, the simplified expression is 5c^6d^2 - 0.5bc^4d + c^6/2.