First find how much soda Danny drank: 1 bottle * .9 = <<1*.9=.9>>.9 bottles
Then find how much soda Danny gave to his friends: 2 friends * 1 bottle/friend * .7 = <<2*1*.7=1.4>>1.4 bottles
Now subtract the soda drunk and given away to find the remaining amount of soda: 3 bottles - .9 bottles - 1.4 bottles = .7 bottles * 100% = 70%
#### 70