Answer: The answer is -4
If you use the chips to help illustrate your point, here's a good way to explain it:
Let's say that there are five -1 chips and one +1 chip. In order to use chips, you would have to subtract the chips from each other. Put a -1 chip and a +1 chip together and then take them away (as to subtract them). This would leave you with four -1 chips, thus giving you your answer.
Hope this helps!