David has $$15$$ more candies than Andy at the beginning. David has $$3$$ candies more than Andy after giving some candies to Andy. How many candies does Debbic give to Aiden? 
Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples
$$15-3=12$, $$8\div 2=4$$. $$\text{D}$$． 