Robert is bringing 625 U.S. dollars with him to Mexico. He needs to exchange the money he has with him to Mexico's currency i.e. from U.S. dollars to Mexican pesos.
The exchange rate is 13.25 Mexican pesos for each U.S. dollar. So 1 U.S. dollar = 13.25 Mexican pesos.
So to calculate how much 625 U.S. dollars is in pesos we multiply 625 with the exchange rate i.e. 13.25 pesos 625 U.S dollars = 625 × 13.25 = 8281.25 Mexican pesos.