David had a total of $$40$$ notes. The notes were either $$$2$$ or $$$10$$ notes. After he spent $$40$$\% of the $$$10$$ notes and $$25$$\% of the $$$2$$ notes on a gift, he had~$\tfrac{4}{5}$~as many $$$10$$ notes as $$$2$$ notes left. How much did the gift cost? 
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