At 11 25, Simon left Town H for Town J, driving at a speed of 81 km/h. At 13 25, Mark also left Town H for Town J driving at a certain speed. Both of them did not change their speed throughout the journey. At 16 25, both of them passed a farm that was 243 km away from Town J. How many minutes earlier did Mark reach Town J than Simon?

Distance that Simon travelled
= 5 x 81
= 405 km

Distance between Town H and Town J
= 405 + 243
= 648 km

Since Mark passed the farm at the same time as Simon, it means that Mark travelled 405 km in 3 hours.

Mark's speed during the journey
= 405 ÷ 3
= 135 km/h

Duration that Mark took to reach Town J after passing the farm
= 243 ÷ 135
= 1.8 h

Duration that Simon took to reach Town J after passing the farm
= 243 ÷ 81
= 3 h

Difference between the time they took to reach Town J
= 3 - 1.8
= 1.2 h

1 h = 60 min
1.2 h = 1.2 x 60 = 72 min

Mark reached Town J 72 minutes earlier than Simon.

Answer(s): 72 min