If NOT Statement Syntax Issues

Question

Can someone explain to me what my syntax should be here? It doesn't seem to change anything not having the = signs.

if(countz > 10 && countz = !20 || countz = !40)

Answer 1

Just trying to guess what it is you want to do, would that be (In english)
"countz greater than 10 but not 20 or 40"

if(countz > 10 && countz !=20 && countz !=40)

Answer 2

I want to say:

If countz is greater than 10 and is not 20 or 40. Thanks for the clues though. I think I see what I did wrong. It seems so obvious looking at your example. haha