Simplify.

a) [[$ -xy \cdot 5 - 3 \cdot 3x =$]]
b) [[$2y \cdot xy + 3x \cdot 4y^2 =$]]
c) [[$-5x \cdot 2y \cdot y +12x \cdot (-y)^2 =$]]
d) [[$-y^2 + (3y)^2 \cdot 2 - 8y \cdot \left( -\dfrac{y}{2}\right) =$]]