Question 34419
The dreaded travelling cars (or trains) -> used to send shivers down my spine in school. Hope I can help now since I kinda understand it.

Basic equation for time = (distance/speed)

If moving in the same direction, relative speed = big speed - small speed
if in opposite directions, relative speed = big speed + small speed

In our case, since the cars are moving in the same direction, relative speed = 71.4-61.4 = 10 Km/hr

distance = 125mtrs = .125Km

so, time taken = {{{ .125/10 }}}= .0125hrs = .0125*60 mts = .0125*60*60 sec

= 45 sec