First of all, don't be afraid
What our teacher teaches us is classified discussion.
When A>0, b > A-B=2-3=- 1。
When A B& lt；, b <; 0，A-B=2-(-3)=5。
When A<0, b > 0，A-B=-2-3=-5。
When A B& lt；, b <; 0，A-B=-2-(-3)= 1。
All right, are you satisfied?