Answer:
-1
For subtraction we will move to the left side on the number line and for the addition right side if they are positive
But for negative, subtraction moving to right side and addition moving to left side
Here we are subtracting -12 from -13 so we will move right side
Now move 12 units to Right side from -13 the answer will be -1
The other way is -13-(-12) is -13+12 is -1