Question 78173
A negative sign really tells you that you are going to use the opposite number. So if you're at 5 on the number line, then -5 means you're going to the opposite side of 5 (which is -5). So -(-5) means the opposite of -5, which is 5 (we're going back now). So in this case, we have 

-(-(-7)))


Lets do the inside:



The opposite of -7 is 7 so we get:
-(-(-7)))=-(7)=-7



So -(-(-7))) simplifies to -7



The rule is when you have 2 negatives, they make a positive (it's like they cancel out)