Car B is traveling.
If you focus on the time. you can see that car A goes farther. so let’s say the line ends at 5 hours for car B and 7 hours for car A (just imagining) Let’s say the top of the line for miles is 20 miles. Since they both end at 20 miles, Car B goes faster, because the line end closer to the origin than line A.
hope this helps sorry if it’s confusing.