The result of $-3 + (-5)$ is $-8$.

Would you like more details or have any questions? Here are some related questions:

1. What is $-6 + (-2)$?
2. How do you add two negative numbers?
3. What is the difference between adding and subtracting negative numbers?
4. What happens when you add a positive and a negative number?
5. What is $-10 + 5$?

Tip: When adding two negative numbers, the result is always negative, and you add the absolute values of the numbers.