A train starts from Delhi with a certain number of passengers. At Ghaziabad 110 get down and 100 get in. At Aligarh 50% get down and 25 get in. At Kanpur 5 of them get down and 50 get in. When train leaves Kanpur there are 200 passengers. How many did board the train at Delhi?

Let the total number of passenger be 'x' that had boarded at Delhi.
Now, at Ghaziabad
110 get down
So the remaining passenger = x - 110
Now again 110 got in
So Net passenger at Ghaziabad = (x - 110) + 100
=x - 10

Now at Aligarh
50% passenger got down
Remaining passenger = \( \Large \frac{x - 10}{2} \)
Now again 25 got in
Net passenger at Aligarh = \( \Large \frac{x - 10}{2} + 25\)

At Kanpur,
5 got down and 50 get in
\( \large \left[ \frac{x - 10}{2} +25\right] - 5 +50 = 200\)
\( \large \left[ \frac{x - 10}{2}\right] = 130\)
X - 10 = 260
X = 270

So the number of passenger boarded at Delhi is 270