This Question Concerns the Mechanism of a Reserve Currency Standard

Essay

This question concerns the mechanism of a reserve currency standard.
Two countries, X and Y, have two currencies, x and y, fixed to the reserve currency, the U.S. dollar. Suppose the exchange rate between x and the U.S. dollar is 3x per dollar. Suppose the exchange rate between y and the U.S. dollar is 5y per dollar. Please explain (using numbers) the mechanism if the x-y exchange rate was 0.8 x per y.