Answer:
-19.67
Explanation:
Given:

As both the number has negative sign, so we need to add both the number as per the rule
Rule:
Minus minus = Plus
Plus plus = Plus
Plus minus= Minus
However, we use sign of largest number; which is -11.29
Now, lets add both the number

We put negative sign with the answer as the highest number have negative sign in the problem.
∴ Answer is -19.67