At 12 30, Vincent left Town L for Town M, driving at a speed of 60 km/h. At 13 30, Charlie also left Town L for Town M driving at a certain speed. Both of them did not change their speed throughout the journey. At 16 30, both of them passed a grocery store that was 120 km away from Town M. How many minutes earlier did Charlie reach Town M than Vincent?

Distance that Vincent travelled
= 4 x 60
= 240 km

Distance between Town L and Town M
= 240 + 120
= 360 km

Since Charlie passed the grocery store at the same time as Vincent, it means that Charlie travelled 240 km in 3 hours.

Charlie's speed during the journey
= 240 ÷ 3
= 80 km/h

Duration that Charlie took to reach Town M after passing the grocery store
= 120 ÷ 80
= 1.5 h

Duration that Vincent took to reach Town M after passing the grocery store
= 120 ÷ 60
= 2 h

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

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

Charlie reached Town M 30 minutes earlier than Vincent.

Answer(s): 30 min