At 14 55, Mark left Town C for Town D, driving at a speed of 87 km/h. At 15 55, Ethan also left Town C for Town D driving at a certain speed. Both of them did not change their speed throughout the journey. At 18 55, both of them passed a school that was 174 km away from Town D. How many minutes earlier did Ethan reach Town D than Mark?

Distance that Mark travelled
= 4 x 87
= 348 km

Distance between Town C and Town D
= 348 + 174
= 522 km

Since Ethan passed the school at the same time as Mark, it means that Ethan travelled 348 km in 3 hours.

Ethan's speed during the journey
= 348 ÷ 3
= 116 km/h

Duration that Ethan took to reach Town D after passing the school
= 174 ÷ 116
= 1.5 h

Duration that Mark took to reach Town D after passing the school
= 174 ÷ 87
= 2 h

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

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

Ethan reached Town D 30 minutes earlier than Mark.

Answer(s): 30 min