Relative speed calculation:

• Since the goods train passes a single point observer (the man) in 9 seconds, the distance covered equals the length of the goods train ($270\text{ m}$).
• Relative speed in m/s:
  $\text{Relative Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{270\text{ m}}{9\text{ s}} = 30\text{ m/s}$.
• Convert relative speed to km/h:
  $\text{Relative Speed} = 30 \times \frac{18}{5} = 108\text{ km/h}$.
• Because the two trains move in opposite directions, relative speed is the sum of their speeds:
  $\text{Speed}_{\text{goods}} + \text{Speed}_{\text{man's train}} = 108\text{ km/h}$.
  $\text{Speed}_{\text{goods}} + 40 = 108 \implies \text{Speed}_{\text{goods}} = 108 - 40 = 68\text{ km/h}$.