其它
James starts classes at $9$ A.M. He has $2$ classes, each class $$45$$ minutes long. After each class, he will take a $$15$$-minute break. When will he finish all $$2$$ classes? 
Overseas Competition->Knowledge Point->Combinatorics->Time Problem
$$45+15+45+15=120$$ minutes = $2$ hours  So, he will finish at $$11:00$$ A.M. 