Answer:
Let's say you have -1 dollars and you want to give that to one person. That would mean -1*1 which is -1 dollars you're giving away in total (you get 1 dollar in total). Now, you negate the one in '-1*1' which means the expression is (-1*(-1)). This means you're taking -1 dollars from one person which basically means you're giving 1 dollar to that person, so you give away 1 dollar in total. You can express this scenario in the expression '1*1', which results in a non-negative number which is 1.
Explanation: