Find the number of solutions to a + b + c = 30, where a, b, c are positive integers.
If a, b, or c = 0, then there is 15 reversable ordered pairs for any of the two other variables adding up to 30.
( a, b ) = 30
( b, c ) = 30
( a, c ) = 30
15 * 3 = 45. Since the ordered pairs are reversable between two variables, 45 * 2 = 90
Similarly, if a, b, or c = 1, then there is 14 reversable ordered pairs for any of the two variables adding up to 29.
14 * 3 * 2 = 84
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I advise to continue on with this method.