At 10 20, Valen left Town E for Town F, driving at a speed of 90 km/h. At 12 20, Oscar also left Town E for Town F driving at a certain speed. Both of them did not change their speed throughout the journey. At 15 20, both of them passed a grocery store that was 180 km away from Town F. How many minutes earlier did Oscar reach Town F than Valen?

Distance that Valen travelled
= 5 x 90
= 450 km

Distance between Town E and Town F
= 450 + 180
= 630 km

Since Oscar passed the grocery store at the same time as Valen, it means that Oscar travelled 450 km in 3 hours.

Oscar's speed during the journey
= 450 ÷ 3
= 150 km/h

Duration that Oscar took to reach Town F after passing the grocery store
= 180 ÷ 150
= 1.2 h

Duration that Valen took to reach Town F after passing the grocery store
= 180 ÷ 90
= 2 h

Difference between the time they took to reach Town F
= 2 - 1.2
= 0.8 h

1 h = 60 min
0.8 h = 0.8 x 60 = 48 min

Oscar reached Town F 48 minutes earlier than Valen.

Answer(s): 48 min