At 14 10, Billy left Town X for Town Y, driving at a speed of 64 km/h. At 17 10, Bobby also left Town X for Town Y driving at a certain speed. Both of them did not change their speed throughout the journey. At 20 10, both of them passed a museum that was 192 km away from Town Y. How many minutes earlier did Bobby reach Town Y than Billy?

Distance that Billy travelled
= 6 x 64
= 384 km

Distance between Town X and Town Y
= 384 + 192
= 576 km

Since Bobby passed the museum at the same time as Billy, it means that Bobby travelled 384 km in 3 hours.

Bobby's speed during the journey
= 384 ÷ 3
= 128 km/h

Duration that Bobby took to reach Town Y after passing the museum
= 192 ÷ 128
= 1.5 h

Duration that Billy took to reach Town Y after passing the museum
= 192 ÷ 64
= 3 h

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

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

Bobby reached Town Y 90 minutes earlier than Billy.

Answer(s): 90 min