Why is positive minus negative positive plus positive?

Answer 1

To subtract a negative number is the equivalent of adding a positive number. Subtracting is the opposite of adding. If adding a negative number is equivalent to subtraction, then subtracting a negative number must be equivalent to addition. A big positive number, such as, let us say, having a large bank account, is the opposite of having a large debt, which would be a negative amount of money. If you owe a thousand dollars, that means you have negative $1000. If you can subtract that debt by paying it off, then you have added $1000 to your net worth. so it makes perfect sense.