Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. If the faster train passes the slower train in 36 seconds,what is the length of each train?  Choose the most appropriate option:
A) 25  B) 30  C) 50  D) 75  E) 40

Rationale: "assume the length of each train = x total distance covered for overtaking the slower train = x + x = 2 x relative speed = 46 - 36 = 10 km / hr = ( 10 × 10 ) / 36 = 100 / 36 m / s time = 36 seconds 2 x / ( 100 / 36 ) = 36 = > ( 2 x × 36 ) / 100 = 36 = > x = 50 meter answer is c ."
Answer: C