Answer:
both train meet at 9.00 pm
Step-by-step explanation:
let t is the time after 1st train start
we know distance = time * speed
D_1 = 40*t
D_2= 60*(t-3) ( as second train depart after 3hr gap)
we know
distance by one train = distance traveled by 2nd train i.e
D_1 = D_2
40*t=60*(t-3)
40*t = 60*t - 60*3
20*t = 180
t = 9
hence both train meet at 9.00 pm