The answer is Amendment 11
Answer:
The Indians traded furs for such goods as tools and weapons. Beaver fur, which was used in Europe to make felt hats, became the most valuable of these furs. The fur trade prospered until the mid-1800's, when fur-bearing animals became scarce and silk hats became more popular than felt hats made with beaver.
If you are familiar with the formula a+b= a2+2ab+b2, this will help you. You have to work backwards and find the common factors. Watch you tube videos and it will show you a x method, where you cross multiply. It is too sophisticated to explain while typing, but hope this will help