Answer:
12 gallons
Step-by-step explanation:
Total gallons = 16 gallons
Total distance = 460 miles
Fuel efficiency in the highway = 30 miles per gallon
Fuel efficiency in the city = 25 miles per gallon
Let
h = gallons of gasoline were used on the highway.
460 = 30h + 25(16 - h)
460 = 30h + 400 - 25h
460 - 400 = 30h - 25h
60 = 5h
h = 60/5
h = 12 gallons
12 gallons of gasoline were used on the highway.