Hey there!
When we subtract a negative, we're doing the same as adding because you're taking away negatives, and you're doing the opposite of subtracting- adding/
Therefore, we have:
-5 + 8
Now, we can think of a number line.
If we have -5 and go 8 to the right because we're adding and getting closer to 0, we'd actually get positive 3 because you'd be going past 0 and into the positives.
Therefore, the answer is positive :)
Hope this helps!