Please explain throughly

29.If the same amount of materials and the same methods are used to produce Big Macs in over 120 countries, why are the prices of Big Macs not, all the same, expressed in dollars?

30.During the late 1980s and early 1990s, American automobile manufacturers greatly increased the quality of cars they produced relative to the cars produced in other nations.What effect do you think this had on American imports of Japanese cars, Japanese imports of American cars and American exports of goods and services other than automobiles?

31A.Who gains and who loses from import restrictions? (Make sure to consider all workers, import-competing industries, consumers, and exporting industries.)

31B.When you go shopping for a new computer, is your real objective to "import" a computer into your apartment, or is it to "export" cash from your wallet?What does this tell you about the true object of international trade - is it exports or imports?