Then the average speed of the plane is 8 kilometers per hour.

Train running 1050km takes (1050/x) hours.

It takes (1050km) hours for the plane to run 1050/(8x).

According to the meaning of the question, list the equations:

1050/(8x) =1050/x-8 and 3/4.

Solution: x= 105

8x=840

So the average speed of the train:105 km/h.

Average speed of aircraft: 840 km/h.