Two wheels, M and N, are placed side by side on a straight road, such as in the figure below. Wheel M has a diameter of 14 feet and Wheel N has a diameter of 21 feet. Both of the two wheels make 3 revolutions per second. Find the distance between the wheels after each wheel has travelled for 8 seconds. (Use π = 22/7)

The
distance between the wheels after each wheel has travelled for 8 seconds is