Can someone explain to me how to find the distance of this story problem?

The "question" ... that's the part you cut off so we can't see it ... is important.

What's the question for Part-A ? Is there also a Part-B ? What's the question in THAT part ?

There are two different questions that could be asked about this train, and they have different answers.

Question #1: What's the total distance the train travels ? That's 10.3 km.

Question #2: What's the train's displacement after it's all over ? That's 2.3 km.

It's pretty tough to find the correct answer when we don't even know the question.

because growing process had stoped after 4-5 year