Hello, I'm kinda lost with this problem: "Find a derivation of this functions:"

$\displaystyle a) z = \frac{exp(2-it)}{exp(2+it)}$

$\displaystyle b) w = (3 + i)z^3exp(3z)$

I really don't know where to start, the only thing that comes to my mind is to "replace" $\displaystyle z$ with $\displaystyle x + iy$. Can someone help me? I would like to solve it by myself, but I need a little help.

Thank you for your time and help.