Subtracting Negative Numbers: Determining the Sign of a-b

We test using an example:

We define that

a = -1

b = -2

Now we replace in the exercise:

-1-(-2) = -1+2 = 1

In this case, the result is positive!

We test the opposite case, where b is greater than a

We define that

a = -2

b = -1

-2-(-1) = -2+1 = -1

In this case, the result is negative!

Therefore, the correct solution to the whole question is: "It's impossible to know".