what's the difference between who&whom and whomever & whoever?
Please be brief & give more than 2 examples

Question

Answer

As a rule of thumb, imagine your phrase saying "him" or "he".

If it makes sense to say "he" then say "who, otherwise say "Whom"

Examples:

Who is guilty? - He is guilty - Accurate
Please send it to him - Sorry, send it to whom? - Accurate.
Let him know. Let who know? - Inaccurate

Answer

This should explain it quite well:

http://web.ku.edu/~edit/whom.html