2011 AIME II Problems/Problem 6
Problem:
Define an ordered quadruple (a, b, c, d) as interesting if 
, and a+d>b+c. How many ordered quadruples are there?
Solution:
There is probably some really complicated formula for this, but as I didnt know it and had 3 hours to "do my best", I listed all possible combinations out. The answer is 80.
