well if she has 15 now then you add 3 to 2 which is 5 then add that to the 15 so you get 20 in total then minus th3 6 she made today you get 14 divided by 2 which is 7 she made 7 yesterday and 13 today which is 20 so the answer is 7
It changed so much because there were always European explorers heading out on voyages, for many reasons (like to trade with neighbouring countries, ferrying people from one land to the other, etc). During those voyages they found new lands, and so the maps had to be revised quite often because of these new discoveries.
