The age of Dr. Pandey is four times the age of his son. After 10 years , the age of Dr. Pandey will be twice the age of his son . The present age of Dr. Pandey's son is
A man starts walking from a place X and reaches the place Y in 12 hours. He travels 3/7th of the total distance at the speed of 3 km/hr and the remaining distance at the speed of 4 km/hr. What is the distance (in km) between X and Y?