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?
