Annie loves giving away puppies. when her friend bobby walks by, she instantly gives him 50% of her puppy stash. bobby, stunned with this shower of puppies, gives back 20% of his total. annie counters by giving bobby 50% of her new puppy total. bobby responds by giving annie back 50% of the puppies he now has and then running off, having gone from 0 to 7 puppies in just a few seconds! how many puppies did annie begin with?