The distance between two railway stations is 1176 km. To cover this distance, an express train takes 5 hours less than a passenger train while the average speed of the passenger train is 70 km/h less than that of the express train. The time taken by the passenger train to complete the travel is:

Answer: Option D

Let the speed of express train = x
Passenger train = x - 70
$$\frac{1176}{x-70}-\frac{1176}{x}=5$$
At x = 168 is satisfy
$$\begin{array}{rl}& \frac{1176}{98}-\frac{1176}{168}=5\\ & 12-7=5\\ & 5=5\end{array}$$
The time of passenger train $$=\frac{1176}{98}=12\text{ hours}$$

Alternate Solution:-
We can go through option
1176 → 1 + 1 + 7 + 6 = 15 → It is divisible by 3.
So, we have to check option, which one is divisible by 3, option A and D
→ Now we can check 18 and 12.