The friend in question 2-18 decides that she does not want to go to Oklahoma after all. How will the costs of your trip change? Was your choice of allocation in question 2-18 incorrect? Why?

Data From Question 2-18:

You and two friends drive your car to Texas for spring break. A third friend asks if you can drop her off in Oklahoma. How would you allocate the cost of the trip among the four of you?