In adding integers, we must remember this steps.
First, you must keep the first number.
The first number is -15, so keep it.
We now have:
-15
Second, you must flip the sign, addition sign will be subtraction sign and vice versa.
The sign is +, so we must make it - .
We now have
-15 -
Third, you must change the sign of the second number, positive becomes negative and vice versa.
The second number is +20, so it is positive, we'll change it to negative, so it becomes -20.
We finally have
-15 - (-20)
Lastly, we must do the operation based on the sign. Apply common sense.
-15 - (-20)
it is like you are paying the money you borrowed, which is 15, and you pay 20. Now your change is going to be five.
-15 - (20) = +5 or simply 5
