Answer
Billy would save $0.52 by going to the less expensive gas station (which is the first gas station).
Step-by-step explanation
At the first station,
c = 2.80g
c = cost of gasoline
g = number of gallons of gasoline
The cost of 1 gallon of gasoline at this station will be obtained by putting in g = 1
c = 2.80g
g = 1 gallon
c = 2.80 (1)
c = 2.80 dollars per gallon
Cost per gallon = 2.80 dollars
At the second station,
2.5 gallons = 8.30 dollars
5 gallons = 16.60 dollars
The cost of 1 gallon at this station will be
1 gallon = (8.30/2.5) = (16.60/5) = 3.32 dollars
Cost per gallon = 3.32 dollars
We can see that gasoline is cheaper at the first station and the difference in price per gallon (which is the amount that will be saved by going to the less expensive gas station) is
3.32 - 2.80 = 0.52 dollars
Hope this Helps!!!