It's called the double negative equals a positive rule... if you added 2 negative #s you'd get the same result. Same thing goes for the English language. For example -6 is the opposite of 6, so if you said "find the opposite of 6" you'd get -6, but if you said "find the opposite of -7," or "find the opposite of the opposite of 11," the "opposite" is negative, which cancels out the 1st negative. This is also classified as "absolute value," and to write them you'd do for 6 -|6|, for -7 |-7|, and for 11 it can be written as -|-|11| or just |-11|. Were you confused when you learned this? So was I!