In all of the cases that I've seen it is usually subtractive, but most of the time it depends on how old the child is.
The advantages of seeing a specialist vs a primary care physician is that the specialist knows exactly about that field of medicine. One circumstance for a specialist: Your eye is bleeding and red, you might want to go see an ophthalmologist because they focus on the eyes. One circumstance for a primary care physician: You feel weak, dizzy and you are vomiting, you have no specific area of pain, so you might want to see a primary care physician because they know about different fields of medicine instead of just focusing on one.
The difference between drugs and medicines is pretty basic, but a lot of people often interchange them. The main thing that differentiates them are their legality and society's perception of them. Both are used for the treatment or cure of diseases, but drugs have a more stimulating and addictive effect to the body than medicine. On the other hand, medicines generally don't have such effects.
The customer buying the debt