A negative number minus a positive number equal?

positive + positive = add (e.g. 2 + 1 = 3)

positive + negative = take (e.g. 2 + -1 = 2 - 1 = 1)

positive - positive = take (e.g. 2 - 1 = 1)

positive - negative = add (e.g. 2 - -1 = 2 + 1 = 3)

negative + positive = add (e.g. -2 + 1 = -1)

negative + negative = take (e.g. -2 + -1 = -2 - 1 = -3)

negative - positive = take (e.g. -2 - 1 = -3)

negative - negative = add (e.g. -2 - -1 = -2 + 1 = -1)