When you negate something which was negative to begin with, what you are actually doing is un-negating it. If it is positive, make it negative and if it is negative, make it positive. This does not work for or you might have been doing this automatically anyway. This will not work with a mixture of signs. Distribution Distribution is useful but is certainly not used as frequently as Demorgan's.
Distribution involves both 's and v's in the same statement.
One part is either inside the parenthesis with each of the other two or it is outside and separate from the parentheses. Notice that the main connective always changes between an and an v. The other connective, then, is the one you put with the other components. Double Negative Double negative is quite simple. If you took what I said in the DeMorgan's section seriously, you are already doing double negation in your head, anyway.