I have a question on the phase of a frequency response

[great1122]

Hello, I'm currently studying for an exam and came across a question I can't seem to figure out. How exactly do we go about calculating the phase of a frequency response. Here is the question, it for part A) iii.

Here are the answers to the other parts and the sketch of the magnitude:

I know you have to add the phases of the H1(w) and H2(w) to get the overall phase but I can't seem to figure out how to get the phase of each one. Any help is appreciated thanks.

 

[milesyoung]

There's a separate forum for homework problems and the like, so, in the future, you should try to use that instead.

For some frequency $\omega$, $H_1(e^{j\omega})$ and $H_2(e^{j\omega})$ are just a couple of complex numbers, so what is $\arg(e^{-j2\omega})$ and $\arg(4)$?