Final answer:
To determine the number of gallons of gas used for city driving, we need to know the fuel economy of the vehicle. Without this information, the question cannot be answered. An example calculation was given using a hypothetical fuel economy of 25 mpg.
Step-by-step explanation:
To calculate how many gallons of gas were used for city driving, we need additional information such as the fuel economy (miles per gallon) of the vehicle used during the trip. This question cannot be answered with the information provided. An accurate calculation requires knowing the vehicle's average miles per gallon (mpg) in city driving conditions. Typically, a vehicle's fuel efficiency is provided in the owner's manual or can be found online.
For instance, if we knew that the vehicle uses 1 gallon of gas every 25 miles in city driving conditions, we could calculate the gallons used for a 504-mile city trip by dividing the total miles by the mpg figure:
504 miles / 25 miles per gallon = 20.16 gallons used
As such, the information about the fuel economy specific to Laura's father's vehicle is critical to solving this problem accurately.