At 10 30, Oliver left Town M for Town N, driving at a speed of 71 km/h. At 12 30, Sean also left Town M for Town N driving at a certain speed. Both of them did not change their speed throughout the journey. At 14 30, both of them passed a farm that was 213 km away from Town N. How many minutes earlier did Sean reach Town N than Oliver?

Distance that Oliver travelled
= 4 x 71
= 284 km

Distance between Town M and Town N
= 284 + 213
= 497 km

Since Sean passed the farm at the same time as Oliver, it means that Sean travelled 284 km in 2 hours.

Sean's speed during the journey
= 284 ÷ 2
= 142 km/h

Duration that Sean took to reach Town N after passing the farm
= 213 ÷ 142
= 1.5 h

Duration that Oliver took to reach Town N after passing the farm
= 213 ÷ 71
= 3 h

Difference between the time they took to reach Town N
= 3 - 1.5
= 1.5 h

1 h = 60 min
1.5 h = 1.5 x 60 = 90 min

Sean reached Town N 90 minutes earlier than Oliver.

Answer(s): 90 min