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