There are 1760 yards in a mile. Because you know that 1 tablespoon of gasoline can be used to drive 125 yards, you would multiply the number of yards, 125, by 256 to find how many miles the car can travel per gallon. $${\mathtt{125}}{\mathtt{\,\times\,}}{\mathtt{256}} = {\mathtt{32\,000}}$$ $${\frac{{\mathtt{32\,000}}}{{\mathtt{1\,760}}}} = {\frac{{\mathtt{200}}}{{\mathtt{11}}}} = {\mathtt{18.181\: \!818\: \!181\: \!818\: \!181\: \!8}}$$
18 is about the number of miles that the vehicle can travel.
If you have any questions feel free to ask!