Answer: -8
Explanation: Arithmetic operations have some precedence according to each other.
Firstly, begin with the operation inside of the parenthesis:

The operation becomes:
-3 + (15) ÷ (-3)
Then, you should do the division part because the division has a precedence according to addition:

Finally, it becomes:
-3 + (-5) = -8
"-8" is the answer.