Explanation:

Let’s break it down step by step:

- Both trains start at the same time, from the same point.

- Train X travels 60 km, then slows down by 25%. Train Y travels 90 km, then also slows by 25%.

- Train X arrives at 10:00 AM. Train Y arrives earlier—at 9:45 AM.

- If neither slowed down, both would reach at 8:30 AM.

What this tells us:

- The slowdown cost them a specific amount of time—1.5 hours for X, 1.25 hours for Y, given the new times.

- Let’s call the original speed V, and let the total distance be D.

- For X: 60/V + (D-60)/(0.75V) = total time

- For Y: 90/V + (D-90)/(0.75V) = total time (arrives 15 mins earlier)

You do the math, set up the equations, and after working it out, the answer is 210 km.

Here’s how the options play out:

- 150 km, 180 km—just too short, given the times lost with the speed reductions.

- 240 km—overshoots based on the journey breakdown.

- 210 km nails it.

So,

The right answer is option 3: 210 km.

That’s the one you want.