$$Sam$$ and $$Tim$$ had $$1170$$ cookies. After $$Sam$$ ate~$\tfrac{1}{4}$~of her cookie and $$Tim$$ bought~$\tfrac{1}{5}$~more cookies, $$Sam$$ had $$663$$ fewer cookies than $$Tim$$. How many cookies did $$Sam$$ eat? 
Overseas Competition->Knowledge Point->Combinatorics->Patterns of Figures->Change of Quantity