Yes.Thank you very much for your easy to understand solution.

Thanks

The solution is erroneous. Tom is not always 15km ahead of Ham.

Tom will only be 15km ahead of Ham if they both changed to the same speed after the point Ham reached the ⅓ mark.


Example :

Let's say the distance of the race is 270km.
They do not change their speeds throughout the journey.


Ham travels at 90km/h.
In 1 hour he travels 90km, which is ⅓ of 270km.

Let's assume Tony travels 15km/h faster.
90km/h + 15km/h = 105km/h

Tony travels at 105km/h. In 1 hour, he travels 105km, which is 15km more than Ham.


Now in 2 hours, Ham has travelled 90km x 2 = 180km

Tony has travelled 105km x 2 = 210km in 2 hours.

210km - 180km = 30km

Tony is now 30km ahead of Ham. The distance between them actually increased. It doesn't remain constant at 15km.

I've just posted the correct solution. Feel free to check it out and clarify any doubts if any.

This question has actually appeared before. There is an error. It should be that Tony's speed is 90km/h.

Thank you J for your correct solution.It was a useful concept that you explained.

Welcome