Friday Puzzle(s)

To get your Friday brain cells in motion, a straightforward problem I've adapted from the puzzles4you.com site:

 1/4 of the hats in Hank's Hat Haberdashery are brown. During a weekend sale, the store sells 2/3 of all their hats, including 4/5 of the brown hats. What fraction of the UNSOLD hats remaining are brown? (answer below)

...and if that one warmed you up, you can give your neurons a further work-out with this "proof" over at Equalis Community Blog that the hypotenuse of a right triangle equals the sum of the two sides!:

http://www.equalis.com/members/blog_view.asp?id=565749&post=122969

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--->  hat answer: 15%