Balard to Paris CDG Airport via T3a and RER-B

I will take tram and train to get Paris Airport CDG, this is the cheapest way to get airport. My hotel was at Balard, close to exhibition center, Paris Expo Porte de Versailles. After leaving the hotel I have taken the T3a tram to Cite Universitare and change to RER-B Paris CDG Airport. Enjoy.