In a journey of three unequal laps, a car covers a distance of 200 km in 4 h in the first lap, while another 162 km at the speed of

15 m/s in the second lap. It covered the remaining distance of the final lap in 4 h such that the average speed of the car for

entire journey was 50 km/h. What was the speed of the car in the third lap of the journey?