Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2xj/ Esercizi: http://www.khanacademy.org/exercises?exid=subtraction_2 Traduzione in Italiano del video Subtraction 2 http://www.youtube.com/watch?v=incKJchBCLo http://www.khanacademy.org/video/subtraction-2?playlist=Arithmetic Help us caption & translate this video! http://amara.org/v/B2xj/