A boys goes to school with a speed of 4 km/hr and returns to the village with a speed of 3 km/hr. If he takes 7 hours in all, the distance between the village and the school is:

Question: A boys goes to school with a speed of 4 km/hr and returns to the village with a speed of 3 km/hr. If he takes 7 hours in all, the distance between the village and the school is:

Solution:
Let the required distance be x km.

Now,
⇒x/4 + x/3 = 7
⇒ (3x + 4x)/12 = 7
⇒ 7x = 84
⇒ x = 12

∴ the distance between the village and the school is 12 km.