At 11 20, Tom left Town M for Town N, driving at a speed of 63 km/h. At 12 20, Tim also left Town M for Town N driving at a certain speed. Both of them did not change their speed throughout the journey. At 15 20, both of them passed a market that was 126 km away from Town N. How many minutes earlier did Tim reach Town N than Tom?

Distance that Tom travelled
= 4 x 63
= 252 km

Distance between Town M and Town N
= 252 + 126
= 378 km

Since Tim passed the market at the same time as Tom, it means that Tim travelled 252 km in 3 hours.

Tim's speed during the journey
= 252 ÷ 3
= 84 km/h

Duration that Tim took to reach Town N after passing the market
= 126 ÷ 84
= 1.5 h

Duration that Tom took to reach Town N after passing the market
= 126 ÷ 63
= 2 h

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

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

Tim reached Town N 30 minutes earlier than Tom.

Answer(s): 30 min