If I'm the admin for the financial system and I want to configure authorization pf file system permission.Also, The first rule is that Managers and clerks can read and write billings for all cases. The second rules is that Paralegals and administrative assits can read and write billings only on cases assigned to their supervising Manager.
how to write these rules in Linux by using ACL approach
There are many web pages desginated to describing how to use ACL's on unix/linux systems, both posix and nfs4 style.
Do you have a specific question about their use? If you are looking for a basic tutorial, google or another search engine is a good place to start.
No, he doesn't. He has a homework assignment, which he is not competent to fulfill and even too lazy to look it up in the way you suggested.
Our traditional answer to such behavior is stony silence. Case closed (and thread too).
bakunin