Para-jumble (foreign exchange basics): Reorder the sentences to define exchange rates, illustrate with major currencies, and show variability with a Mexico example. S1 = "Payment for imports and exports is made through a system called foreign exchange." S6 = "Another time it may be worth eight pesos." Between S1 and S6, arrange definition → illustration → variability: 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." Choose the correct sequence of P–Q–R–S that completes the paragraph.