Provide answer with around 100 words for each question. (18 points total) 1. As a result of the North America Free Trade Agreement (NAFTA), the United States and Canada have shifted to free trade with Mexico. It is assumed that Mexico has an abundance of unskilled labor while the United States and Canada have an abundance of skilled labor. According to the StolperSamuelson theorem, how this shift will affect the real wage of unskilled labor in Mexico and the real wage of unskilled labor in the United States and Canada? Also explain the impact on the real wage of skilled labor in Mexico and skilled labor in the United States and Canada. Explain the concept of scale economies. Explain the difference between internal and external scale economies. What pattern of trade do we expect to see in industries with substantial external scale economies? . Why does the HO theory predict that most research and development activity is done in the industrialized countries