Hey the 3 free means that you save 15$. it doesn't mean you get 13 booster packs.The 3 free are included as you pay 35$ which is equal to 7 boosterpacks if that makes any sense.
well not really XD , i work so each month i take out 100 or 150 $ for games and other things and the rest is for me to live on for the month. but hey its all good.