A man travels some distance at a speed of 12 km/hr and returns at a speed of 9 km/hr. If the total time taken by him is 2 hr 20 min, the distance is :

A. 35 km

B. 21 km

C. 9 km

D. 12 km

Answer: Option D

Solution(By Examveda Team)

Let the distance be x km
According to the question,
$$\eqalign{ & \frac{x}{{12}} + \frac{x}{9} = 2 + \frac{{20}}{{60}} \cr & \frac{{3x + 4x}}{{36}} = \frac{7}{3} \cr & \frac{{7x}}{{36}} = \frac{7}{3} \cr & \boxed{x = 12{\text{ km}}} \cr} $$