Answer:
B. 7.4 gal
Step-by-step explanation:
Let x represent the number of gallons of gas needed to complete the trip.
Given that Zara drove 168 miles on 8 gallons of gas, if she had 155 miles left to complete her trip, we can go ahead and determine x by setting up proportions as shown below;

If we cross multiply, we'll have;

Let's now divide both sides of the equation by 168;

Therefore, Zara would need 7.4 gallons of gas to complete her trip.