If a person walks at 14 km/hr instead of 10 km/hr, he would have walked 20 km more. The actual distance travelled by him is:

(a) 50 km

(b) 56 km

(c) 70 km

(d) 80 km

Explanation:
Let the actual distance travelled be x km.
Then, x/10 = (x + 20)/14
=> 14x = 10x + 200
=> 4x = 200
=> x = 50 km.