The revolutionary mathematical theory composed by Austin Hall that states that a subtraction or addition problem which gives the result of a negative number can in fact be interpreted to be negative or positive, whichever you decide.
"So, class we see that 3 - 6 = -3."
"Ah, Mr. Teacher, you're forgetting Austin's Law!"
"Oh, of course! It can be -3 or +3. You can decide!"