question: Alfie, the albatross, flies 400 kilometers every day.  If the circumference of the earth is 40,000 kilometers, how many days will it take Alfie to fly a distance equal to half of the way around the earth?
answer: Half of 40,000 kilometers is 40,000/2=<<40000/2=20000>>20,000 kilometers.
  At 400 kilometers per day, it will take Alfie 20,000/400=50 days to fly a distance equal to half the earth's circumference.
  #### 50