Tom travelled to the train station at 60 mph and arrived 1 minute earlier. He then travelled back home at 30 mph and arrived 1 minute late. How long was the trip.

D= 60 * T - 1 + 30*T+1
60T+30T -1+1
90 t

sounds like the time difference between trips was 2 minutes (1/30 hr). Since time=distance/speed,

d/30 - d/60 = 1/30
d = 2