In a very popular Chinese restaurant, all seats were filled and there were still $$8$$ customers in line outside the door. After some time, $$11$$ customers finish eating and leave the restaurant, and then $$15$$ more customers join the waiting line. How many people are still in line outside the door? 
Overseas Competition->Knowledge Point->Word Problem Modules->Applying Addition and Subtraction->Simple Addition and Subtraction
The line at the door started with $$8$$ people and $$15$$ more came in, for a total of $$23$$ people. After leaving $$11$$ customers, $$11$$ seats were empty, so the number of people left in line was $$23-11=12$$. 