well?

We use "-" to denote two separate ideas. First, "-a" simply means the inverse of "a" in whatever group you're working with. Second, "a - b" is just shorthand for "a + (-b)". Thus, "4-(-4)" is equivalent to "4 + -(-4)" and "-(-4)" is simply 4 by the the uniqueness of additive inverses. Thus, "4-(-4) = 4+4 = 8".

It's best to pretend subtraction doesn't exist. Treat it as addition by the inverse instead.