U have to list the factors so i can answer the question
Answer: Water, horse and saddle, Wagon, car
Explanation:
27 is a factor of 54 so 27
The biggest doubling time of all the regions/continents in the world has Europe.
Europe is the only continent that has almost 0% population growth (as of 2014), which practically means that with this pace Europe will need an eternity to be able to double its population, so it makes it the continent with the biggest time needed to double it's population.
