Let the speed of train B be s. SB = s Speed of train A, SA = 2s Total distance, D = 120 km Total time taken to meet, T = 2 hours ∵ Trains are moving in opposite directions, Relative speed of trains = s + 2s = 3s 3s = 120/2 s = 20 km/h ∴ The speed of train A is 40 km/h.