Final answer:
The ferry uses 6.2 gallons of fuel to complete the route one time.
Step-by-step explanation:
To find the total number of gallons the ferry uses to complete the route one time, we need to calculate the total distance traveled and then divide it by the fuel efficiency of the ferry.
The ferry travels 8 miles due south from Seabreeze Village to Oceanview. Then it travels 15 miles due east from Oceanview to Portlandville. Finally, it makes a straight-line journey back to Seabreeze Village, which we can assume is the same distance as the initial leg.
Therefore, the total distance traveled is 8 + 15 + 8 = 31 miles.
Since the ferry can travel 5 miles on a gallon of fuel, we divide the total distance by the fuel efficiency to find the number of gallons used:
31 miles / 5 miles per gallon = 6.2 gallons.