At 11 40, Howard left Town E for Town F, driving at a speed of 75 km/h. At 12 40, Luis also left Town E for Town F driving at a certain speed. Both of them did not change their speed throughout the journey. At 15 40, both of them passed a school that was 150 km away from Town F. How many minutes earlier did Luis reach Town F than Howard?

Distance that Howard travelled
= 4 x 75
= 300 km

Distance between Town E and Town F
= 300 + 150
= 450 km

Since Luis passed the school at the same time as Howard, it means that Luis travelled 300 km in 3 hours.

Luis's speed during the journey
= 300 ÷ 3
= 100 km/h

Duration that Luis took to reach Town F after passing the school
= 150 ÷ 100
= 1.5 h

Duration that Howard took to reach Town F after passing the school
= 150 ÷ 75
= 2 h

Difference between the time they took to reach Town F
= 2 - 1.5
= 0.5 h

1 h = 60 min
0.5 h = 0.5 x 60 = 30 min

Luis reached Town F 30 minutes earlier than Howard.

Answer(s): 30 min