How do you know if your answer is going to be negitive or positive?

Question

Ex:

-7.8+9.8-

Answer 1

If you add 2 negative values, the answer will always be negative.

If you add 2 positive values, the answer will always be positive.

If you add a positive and negative value, compare the absolute value of the two. If the absolute values are equal, the result is zero. If the absolute value of the positive number is larger than the absolute value of the negative value, the result is positive. Otherwise, the result is negative.