Fuel mileage question

[landon4421]

After reading a few differant post on fuel mileage. I wanted to know what kind of mileage Jenna's 71 was getting? So I started to keep track of the fuel and mileage. The only thing is I have never tryed or had to figure out what the fuel mileage is. could someone show me how? Here is the #'s I have.

12.2 gallons 15730 mileage
13.5 gallons 15908 mileage
11.8 gallons 16047 mileage
11.5 gallons 16191 mileage

I have been trying to keep track but the wife fills up and forgets to write down the mileage. I hope I am getting decent mileage, but I totally think it is pritty crappy.