In the question given below, the passage consists of six sentences. The first and sixth sentences are given at the beginning. The middle four sentences have been removed and jumbled up. They are labelled as, P, Q, R, and S. Find out the proper order for the four sentences.
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