At 12 35, Justin left Town N for Town P, driving at a speed of 84 km/h. At 13 35, Harry also left Town N for Town P driving at a certain speed. Both of them did not change their speed throughout the journey. At 17 35, both of them passed a salon that was 168 km away from Town P. How many minutes earlier did Harry reach Town P than Justin?

Distance that Justin travelled
= 5 x 84
= 420 km

Distance between Town N and Town P
= 420 + 168
= 588 km

Since Harry passed the salon at the same time as Justin, it means that Harry travelled 420 km in 4 hours.

Harry's speed during the journey
= 420 ÷ 4
= 105 km/h

Duration that Harry took to reach Town P after passing the salon
= 168 ÷ 105
= 1.6 h

Duration that Justin took to reach Town P after passing the salon
= 168 ÷ 84
= 2 h

Difference between the time they took to reach Town P
= 2 - 1.6
= 0.4 h

1 h = 60 min
0.4 h = 0.4 x 60 = 24 min

Harry reached Town P 24 minutes earlier than Justin.

Answer(s): 24 min