The constant of variation and the slope of the line that passes through each pair of points

Omar is going on a road trip! the car rental company offers him two types of cars. each car has a fixed price, but he also needs to consider the cost of fuel. the first car costs $90 to rent, and because of its fuel consumption rate, there's an additional cost of s0.50 per kilometer driven.

Me with this one question, and i'll upvote the brainliest answer

What is the greater volume 72 quarts or 23 gallons