Answer: 17.5 gallons
Explanation:
The formula to solve this question will be: g = d/m
where, g = number of gallons of gasoline used
d = distance travelled = 315 miles
m = miles per gallon = 18 miles/gallon
Therefore, the number of gallons of gasoline that Darnell will need to travel 315 miles will be:
g = d/m
g = 315/18
= 17.5 gallons