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

The Proper sequence should be: