Khan/khan-exercises — pull request #24773 by petercollingridge (2012-06-24 22:08:12+00:00)
Title: Integer sum exercise

I made an exercise corresponding to these two videos:

http://www.khanacademy.org/math/algebra/solving-linear-equations/v/integer-sums
http://www.khanacademy.org/math/algebra/solving-linear-equations/v/sum-of-consecutive-odd-integers