Answer
$$11y^{3}-18y^{2}-4y$$
Work Step by Step
Initial Equation: $-y(y^{2}-4)+6y^{2}(2y-3)$
Distribute the $-y$ and $6y^{2}$ to their respective parenthesis:
$$-y^{3}-4y+12y^{3}-18y^{2}$$ Then, combine like terms to arrive at final answer:
$$11y^{3}-18y^{2}-4y$$