Under a fixed exchange rate system, setting the official price of a peso in terms of dollars

Question:

Under a fixed system, setting the official price of a peso in terms of dollars automatically sets the official price of a dollar in terms of pesos. Do you agree or disagree? Explain.
Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...