Provide a 300-plus word description of each topic: The main reason for international trade, what gains derive from it, the conditions of the U.S. balance of payments, aspects of terms of trade, the main trade barriers and efforts to eradicate them, the arguments for protectionism and a comparison of the latter to the pros/cons of free trade; use graphs, formulas and examples to support your findings. Also address international finance, the evolution of the exchange systems, what affects currency rates and how those in turn influence prices, output and trade flows. Conclude with your outlook on the u.S. trade balance.