[nongtum]

The 21. problem lacks some infos to make the answer unique (e.g. a,b are natural numbers). If this were given, so it could be seen that (72+b)a=395=79*5, which implies a=7, b=5 and (p-1)/ab=1.

46. He he he, sorry. I was totally careless.

PS: will be edited in thai later if needed, I've no access on my comp now btw...
Edit1: A lil'bit typos corrected.