Wow the peso to dollar is now 20.26 pesos to one US dollar. It is in your best interest to use pesos. See the new chart in the lower right hand corner.
That is great 30 years of going to Mexico I have never seen it that high. Most years going I used 10 pesos to one US$ . So if you are not real good at math use the chart because US dollar is worth a lot more. So if you saw something for 150 pesos you would say 15$ but now that would be $7.50.