At 13 40, Ian left Town R for Town S, driving at a speed of 84 km/h. At 14 40, Luis also left Town R for Town S driving at a certain speed. Both of them did not change their speed throughout the journey. At 18 40, both of them passed a church that was 168 km away from Town S. How many minutes earlier did Luis reach Town S than Ian?

Distance that Ian travelled
= 5 x 84
= 420 km

Distance between Town R and Town S
= 420 + 168
= 588 km

Since Luis passed the church at the same time as Ian, it means that Luis travelled 420 km in 4 hours.

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

Duration that Luis took to reach Town S after passing the church
= 168 ÷ 105
= 1.6 h

Duration that Ian took to reach Town S after passing the church
= 168 ÷ 84
= 2 h

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

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

Luis reached Town S 24 minutes earlier than Ian.

Answer(s): 24 min