Mexican coins are produced in such great quantity that they are rarely worth more than their face value. The value of the metal in the coin is often worth more than the exchange. Mexican coins are best valued by the pound than individually. Do you know how much its worth.
In the United States, a Mexican Peso is not worth much more than three cents or so. Although, check the date and variety of your coin, because if it is older or different than present Mexican coins, dealers would probably pay you a bit more.
If the it's dated 1993 or later it's an ordinary circulation coin worth about 20 cents. If it's older, please post a new question with the coin's date. Also note that on Mexican currency the "$" sign stands for pesos, not dollars.
20.00 Mexican Pesos are worth 1.56$ USD or 1.57$ CAD. That being said, there is no international banking exchange of coin currency. Only papered currency. This means that your 20 pesos are only worth that in Mexico!
it cost over $100,000,000,000 here in america as if it was n10 the whole country would not be able to afford that mexican coin because of the economy that hve been wasted on un important stuff that arent needed fools.