Calculate the Sum: (-0.73) + (-13.07) Decimal Addition

Let's remember the rule:

$+(-x)=-x$

Now let's write the exercise in the appropriate form:

$-0.73-13.07=$

Since we are subtracting a larger number from a smaller number, the result will be negative.

We'll combine the two numbers together vertically, but remember that the result will be negative:

$0.73\\+13.07\\13.80$

Therefore, the answer is:

$-0.73-13.07=-13.8$