A survey of all students in the class reveals that $$20$$ students can swim, and $$25$$ students can play basketball. In addition, $$10$$ students can do both, and $$9$$ students can do neither. Find the total number of students in this class. 
Overseas Competition->Knowledge Point->Counting Modules->Inclusion-Exclusion Principle->Inclusion-Exclusion Principle for Two Sets Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations