At 11 35, Riordan left Town K for Town L, driving at a speed of 77 km/h. At 14 35, Eric also left Town K for Town L driving at a certain speed. Both of them did not change their speed throughout the journey. At 17 35, both of them passed a boutique that was 231 km away from Town L. How many minutes earlier did Eric reach Town L than Riordan?

Distance that Riordan travelled
= 6 x 77
= 462 km

Distance between Town K and Town L
= 462 + 231
= 693 km

Since Eric passed the boutique at the same time as Riordan, it means that Eric travelled 462 km in 3 hours.

Eric's speed during the journey
= 462 ÷ 3
= 154 km/h

Duration that Eric took to reach Town L after passing the boutique
= 231 ÷ 154
= 1.5 h

Duration that Riordan took to reach Town L after passing the boutique
= 231 ÷ 77
= 3 h

Difference between the time they took to reach Town L
= 3 - 1.5
= 1.5 h

1 h = 60 min
1.5 h = 1.5 x 60 = 90 min

Eric reached Town L 90 minutes earlier than Riordan.

Answer(s): 90 min