At 11 30, Xavier left Town Q for Town R, driving at a speed of 75 km/h. At 13 30, Japheth also left Town Q for Town R driving at a certain speed. Both of them did not change their speed throughout the journey. At 16 30, both of them passed a farm that was 225 km away from Town R. How many minutes earlier did Japheth reach Town R than Xavier?

Distance that Xavier travelled
= 5 x 75
= 375 km

Distance between Town Q and Town R
= 375 + 225
= 600 km

Since Japheth passed the farm at the same time as Xavier, it means that Japheth travelled 375 km in 3 hours.

Japheth's speed during the journey
= 375 ÷ 3
= 125 km/h

Duration that Japheth took to reach Town R after passing the farm
= 225 ÷ 125
= 1.8 h

Duration that Xavier took to reach Town R after passing the farm
= 225 ÷ 75
= 3 h

Difference between the time they took to reach Town R
= 3 - 1.8
= 1.2 h

1 h = 60 min
1.2 h = 1.2 x 60 = 72 min

Japheth reached Town R 72 minutes earlier than Xavier.

Answer(s): 72 min