1. State the problem: Prove that $-(-a) = a$ for any number $a$. 2. Understand the sign notation: The negative sign $-$ before a number means the additive inverse of that number. 3. Start with the expression $-(-a)$. 4. By definition, $-a$ is the number which, when added to $a$, gives zero: $$a + (-a) = 0$$ 5. Now, $-(-a)$ means the additive inverse of $-a$, so it is the number which, when added to $-a$, yields zero: $$-a + (-(-a)) = 0$$ 6. From step 4, since $a + (-a) = 0$, by uniqueness of additive inverses, $-(-a)$ must be equal to $a$. 7. Therefore, $$-(-a) = a$$ This completes the proof that the negative of the negative of any number $a$ is $a$ itself.