At 12 30, Zeph left Town A for Town B, driving at a speed of 75 km/h. At 14 30, Liam also left Town A for Town B driving at a certain speed. Both of them did not change their speed throughout the journey. At 17 30, both of them passed a library that was 150 km away from Town B. How many minutes earlier did Liam reach Town B than Zeph?
Duration that Zeph travelled from 12 30 to 17 30 = 5 h
Distance that Zeph travelled
= 5 x 75
= 375 km
Distance between Town A and Town B
= 375 + 150
= 525 km
Since Liam passed the library at the same time as Zeph, it means that Liam travelled 375 km in 3 hours.
Liam's speed during the journey
= 375 ÷ 3
= 125 km/h
Duration that Liam took to reach Town B after passing the library
= 150 ÷ 125
= 1.2 h
Duration that Zeph took to reach Town B after passing the library
= 150 ÷ 75
= 2 h
Difference between the time they took to reach Town B
= 2 - 1.2
= 0.8 h
1 h = 60 min
0.8 h = 0.8 x 60 = 48 min
Liam reached Town B 48 minutes earlier than Zeph.
Answer(s): 48 min
