其它
Joann and Sana have $20$ dresses in total. Joann gives half of her dresses to Claire, and then she and Sana have $14$ dresses in total. How many dresses does Sana have? 
Overseas Competition->Knowledge Point->Counting Modules
Joann gives $20-14=6$ dresses to Claire.  Joann has $6+6=12$ dresses originally.  Sana has $20-12=8$ dresses. 