Your answer would be -9 
Remember To ↓
Negative and Negative = Positive
Negative and Positive = Negative
Positive and Negative = Negative
 Positive and Positive = Positive 
 
Negatives is always goes to the left side on a timeline (downward) while Positives on the other hand, always goes to the right side on a timelime (upward)
Sometimes, we can change the symbols in integers 
For this equation we replaced the addition to a subtraction