[A]. 10
[B]. 18
[C]. 36
[D]. 72
✅ The correct answer is option C.
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
So, 2x =
(120 + 120)
12
2x = 20
x = 10.
Speed of each train = 10 m/sec =
10 x
18
km/hr = 36 km/hr.
5