Question 629126
The two friends are getting closer to each other at a combined speed of (6 + 14) km/h = 20 km/h.

Time = Distance/speed
The time taken to travel 4 km at a speed of 20 km/h is
4/20 =0.2 hours
0.2 hour is 0.2 x 60 = 12 minutes
i.e. they meet after 12 minutes