I agree with the others: go look for other textbooks. There are also surprisingly good "webinar's" on various math related topics on YouTube (free), so it might be worthwhile to have him do a bit of searching.
Oddly, I never had any discrete math courses in school...it was "old school EE" so everything was differential equations and stochastic processes. I did end up teaching myself about finite fields (Galios Fields to be specific) when I needed to do some work with error correcting codes. I ended up with 3 or 4 different textbooks on the topic. I have since gone back to refresh myself about them and found several good video courses on YouTube. TTFN - Guy
