Solution:

Let the length of the bridge be x meters.
Running towards the train, Charles covers 0.5x-10 meters in the time that the train travels x-4 meters. Running away from the train, Charles covers 0.5x+2 meters in the time that the train travels 2x-8 meters.

Because their speeds are constant, the following holds:

(0.5x-10) / (x-4) = (0.5x+2) / (2x-8)
which can be rewritten to
0.5x2 - 24x + 88 = 0
Using the abc formula we find that x=44, so the railway-bridge has a length of 44 meters.

Solution:

The riddle, the 'facts' of which may or may not be true, results in the following equation:

x/6 + x/12 + x/7 + 5 + x/2 + 4 = x

where x is Abhishek's age at the time of his death.

Therefore, salmna lived exactly 84 years.

Solution:

A Door

Solution:

Jack and Jill are the names of two clown fishes. Unfortunately the bowl they were living in fell on the floor and broke into pieces. Thus both of them died.

Solution:

Yes it is possible if you just remove 's' from seven. It will then become even.

Solution:

once upon a time

Solution:

For Instance