#### Answer

(a) $\frac{d}{dt}ct^3=3ct^2$.
(b) $\frac{d}{dz}(5z+4cz^2)=5+8cz $.
(c) $\frac{d}{dy}(9c^2y^3-24c)=27c^3y^2
$.

#### Work Step by Step

Since $ c $ is constant, we have
(a) $\frac{d}{dt}ct^3=3ct^2$.
(b) $\frac{d}{dz}(5z+4cz^2)=5+8cz $.
(c) $\frac{d}{dy}(9c^2y^3-24c)=27c^3y^2
$.