At 13 40, Dylan left Town K for Town L, driving at a speed of 86 km/h. At 16 40, Henry also left Town K for Town L driving at a certain speed. Both of them did not change their speed throughout the journey. At 19 40, both of them passed a mall that was 258 km away from Town L. How many minutes earlier did Henry reach Town L than Dylan?

Distance that Dylan travelled
= 6 x 86
= 516 km

Distance between Town K and Town L
= 516 + 258
= 774 km

Since Henry passed the mall at the same time as Dylan, it means that Henry travelled 516 km in 3 hours.

Henry's speed during the journey
= 516 ÷ 3
= 172 km/h

Duration that Henry took to reach Town L after passing the mall
= 258 ÷ 172
= 1.5 h

Duration that Dylan took to reach Town L after passing the mall
= 258 ÷ 86
= 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

Henry reached Town L 90 minutes earlier than Dylan.

Answer(s): 90 min