There is a straight highway. Four different villages lie on that highway. The distance between them is different. The third village is 60km away from the first village; the fourth is 40 km away from the second; the third is 10 km near to the fourth that it is to the second.

Can you calculate the distance between the fourth and the first village?

Solution: 75

First Village = A

Second Village = B

Third Village = C

Fourth Village = D

Distance between B and D = 40km

=> Distance between B and C + Distance between C and D = 40km

=> Distance between B and C + (Distance between B and C - 10) = 40 km

=> 2 * Distance between B and C = 50km

=> Distance between B and C = 25km

Therefore the distance between C and D = 15km

Thus, distance between A and D = 60 + 15 = 75km.