Boolean rules are bugging me

I just encountered a propably simple problem with booleans

If I have an if statement like this one: !(!A && !B) && B, how does it exactly go?

I thought it was the same as A && B (inverts the conditions inside the brackets), but it obviously wasnt.. which is bugging me

So, would someone like to elaborate how it really goes because I think I'm missing something here?

Thanks.