Answer:
Frictional force is produced when two bodies are rubbed against each other. It is the force that oppose the motion and therefore it stops or slow down a moving body.It depends upon the roughness or smoothness of the surface of the body in contact.Rough surface have more friction that the smooth surface. Similarly, the heavier body produces more friction than a lighter body. Frictional force acts in the opposite direction of the motion of the body.
Distance = speed x time. The total speed is 30 + 60 = 90km/h and the total time taken is 15 + 15 = 30 minutes. Therefore, you do 90 x 30 = 2700km
Answer = 2700km