On morning Joy was walking on a grass-way in a garden.Wind was also blowing in the direction of his walking with speed `u`.He suddenly saw his friend Kim walking on the parallel grass-way at a distance `x` away.Both stopped as they saw each other when they were directly opposite on their ways at a distance `x`.Joy shouted "Hi Kim".Find the time after which Kim would have heard his greeting.Sound speed in still air is `v`.