A boy is traveling to a destination. If he moves at a

Solution

Let the distance and time taken by boy to reach his destination if he travels at his usual speed be 'D' metres and 'T' seconds, respectively. Using, distance = speed X time 'D' = 20 X (T + 20) ------ (I) And, 'D' = 40 X (T - 10) --------- (II) From equations (I) and (II) , We have; 20 X (T + 20) = 40 X (T - 10) Or, T + 20 = 2T - 20 Or, 'T' = 40 On putting 'T' = 40 in equation (I) , We have, 'D' = 20 X (40 + 20) = 1,200 metres = 1.2 km