Question 556194
if you travelled by foot, bicycle, rollerblades, skateboard, electric car, hot air balloon, solar car or any other means without gas then its a 0 gallons. if your in a gas guzler like an suv with 5 miles to a gallon or a 30 gallon take then there might be some possible way to find out the mi/g. 

for example an actual problem would be:
if i traveled 200 miles in my car with a 22 gallon tank, what would be my average mile per gallon estimate?

but seems how you traveled that far without naming your transpetation it seems rather impossible to find a answer. and esp without a time limit to narrow down the possibilities. it could be that it took you 200 days to walk 200 miles.