A man completes a journey in 16 hours.  He travels at a speed of 15 km/h for the first half of the journey and at a speed of 25 km/h for the second half.  Calculate the total distance travelled (in km).

300

Total time = 5 + 3 = 8 Units

8 Units → 16 hours

1 Unit  → 2 hours

75 Units  → 75 × 2 = 150 

Total distance = 150 × 2 = 300 km