Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2xZ/ Esercizi: http://www.khanacademy.org/exercises?exid=adding_and_subtracting_negative_numbers Traduzione in Italiano del video Adding/Subtracting negative numbers http://www.youtube.com/watch?v=C38B33ZywWs http://www.khanacademy.org/video/adding-subtracting-negative-numbers?playlist=Pre-algebra Help us caption & translate this video! http://amara.org/v/B2xZ/