50's Newbie loves excel but ....

Hi everyone,

I love the things you can do in excel(and try to learn cool things everyday) but a lot of the info goes over my head....i need simple formulas (after all I learned to type on a manual typewriter LOL).

trying to get a formula to help my boss (just as lost as me) set up a fuel chart that shows gas mileage effectively gallons bought, miles traveled between fill-ups, mileage before and after fillup= mpg.

is there a simple formula?

Thanks

confused....