Solving (-13)+(-12): Adding Negative Numbers on a Number Line

Let's first locate negative 13 on the number line.

Now let's deal with the operation in the exercise, given that the operation is $+(-12)$

Since negative 12 is less than 0, we will move twelve steps to the left from negative 13, where each step represents one whole number as follows:

We can see that the number we reached is negative 25.