For the first gas station,
![c=2.80g](https://img.qammunity.org/2023/formulas/mathematics/college/u9z8bsg8qpi5xwo11o9wl2gt9ln2mllkmg.png)
That is, for one number of gallon of gasoline, the cost is, 2.80
For the second gas station, cost of 2.5 gallons of gasoline is $8.30. Therefore, for one gallon if gasoline, the cost is,
![(8.30)/(2.5)=3.32](https://img.qammunity.org/2023/formulas/mathematics/college/v0k963sbxis44hcgwgejt4tic7t2pfabp7.png)
Therefore, Billy will save, 3.32 - 2.80 = 0.52 dollars by going to the less expensive gas station.