Please refer to the solution and then state which step you didnt understand

here how it is decided that ajay left minu y km from the hospital to pick up sonu and they will reach the destination together just by leaving minu at y km from the hospital

It is decided based on the fact that minu and sonuboth can walk at 4kmph speed

rc mock 18 Screenshot 2024-10-15 194946.png 51.22 KB