S1 : Payment for imports and exports is made through a system called foreign exchange.
S6 : Another time, it may be worth eight pesos.
P : The value of the money of one country in relation to the money of other countries is agreed upon.
Q : Theses rates of exchange vary from time to time.
R : For instance, and American dollar or a British pound sterling is worth certain amounts in the money of other countries.
S : SOmetimes, a United Stated dollar is worth 12 pesos in Mexico.
The proper sequence should be