A person travelled a distance of 610 km in 9 hours. He travelled the first phase at a speed of 40 kmph…

Let the first part be $x$ km. Then $\tfrac{x}{40} + \tfrac{610 - x}{90} = 9$; multiplying by 360 gives $9x + 2440 - 4x = 3240$, so $5x = 800$ and $x = 160$.

Check: 160 km at 40 kmph takes 4 hours and 450 km at 90 kmph takes 5 hours, 9 hours in all.