how to answer the physics problem

Not just the answer. But the reason and the correct step in solving the problem.
There are 3 ways to solve the problem, there may even be other ways not about the formula let alone how to cepqt, but essentially how we simplify the problem to be solved in simple model2.

• Version 1 using relative speed
• Version 2 assumes the travel time of both cars is the same
• Version 3 makes the equation of second mileage.