a is a positive number.
b is a negative number.
The sum of a+b is...?
a is a positive number.
b is a negative number.
The sum of a+b is...?
We will use trial and error in order to test this:
Let's assume that the value of the positive number is greater than the value of the negative number 1 and 2.
1+(-2) = -1
The result is negative.
We will try to make the value of the second number greater than the first 2 and 1.
2+(-1)= 1
The result is positive.
That is, we can see that the result depends on the values of the two numbers, so we cannot know from the beginning what the result will be.
It is not possible to know.