At 10 45, Oscar left Town S for Town T, driving at a speed of 72 km/h. At 11 45, Ian also left Town S for Town T driving at a certain speed. Both of them did not change their speed throughout the journey. At 15 45, both of them passed a market that was 144 km away from Town T. How many minutes earlier did Ian reach Town T than Oscar?

Distance that Oscar travelled
= 5 x 72
= 360 km

Distance between Town S and Town T
= 360 + 144
= 504 km

Since Ian passed the market at the same time as Oscar, it means that Ian travelled 360 km in 4 hours.

Ian's speed during the journey
= 360 ÷ 4
= 90 km/h

Duration that Ian took to reach Town T after passing the market
= 144 ÷ 90
= 1.6 h

Duration that Oscar took to reach Town T after passing the market
= 144 ÷ 72
= 2 h

Difference between the time they took to reach Town T
= 2 - 1.6
= 0.4 h

1 h = 60 min
0.4 h = 0.4 x 60 = 24 min

Ian reached Town T 24 minutes earlier than Oscar.

Answer(s): 24 min