Answer: 16.5 m/s towards East
Explanation: The man walks on the bus. For stationary observer, the bus moves towards East at a speed of 18 m/s. The man moves in the opposite direction i.e. towards west at a speed of 1.5 m/s. Thus, the relative speed of the man with respect to the stationary observer would be:
V = 18 m/s - 1.5 m/s = 16.5 m/s towards East.
Thus, the velocity of the man in the frame of reference of stationary observer is 16.5 m/s towards East.