4. One way to equalize imports and exports would be to pass a law that (1) in order to import, importers must provide a certificate certifying that an equal value of exports had occurred; and (2) in order to export, exporters must provide a certificate certifying that an equal value of imports had occurred.

a. If the trade is balanced, what would the price of these certificates be?

b. In the current U.S. situation, what would the price of these certificates be?

c. In the current Chinese situation, what would the price of these certificates be?

d. Would such a law make exchange rate adjustment more or less likely?