If there is 10% inflation in Brazil, 15% inflation in Argentina, and the Argentine peso weakens by 21% relative to the Brazilian real, by how much has the peso strengthened or weakened in real terms?...

If there is 10% inflation in Brazil, 15% inflation in Argentina, and the Argentine peso weakens by 21% relative to the Brazilian real, by how much has the peso strengthened or weakened in real terms? What effect do you expect that this change in the real exchange rate would have on trade between the two countries?