Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2ty/ Esercizi: http://www.khanacademy.org/exercise/adding_negative_numbers Traduzione in Italiano del video Adding Negative Numbers http://www.youtube.com/watch?feature=player_embedded&v=AcpIO62x2oo http://www.khanacademy.org/math/arithmetic/addition-subtraction/v/adding-negative-numbers