Question
 Harsh covers a certain distance with his own speed,
but when he reduces his speed by 20 km/hr his time duration for the journey increases by 80 hrs, while if he increases his speed by 10km/hr from his original speed he takes 20hrs less than the original time taken. What is the distance covered by him?Solution
Let distance be x km and speed be y km/hr x/(y - 20) - (x/y) = 80   x = 4y(y - 20) .............(1) (x/y) - x/(y + 10) = 20 x = 2y(y + 10) ..............(2) From (1) and (2), we get 4y(y - 20) = 2y(y + 10) 2y - 40 = y + 10 y = 50 km/hr Then x =2 × 50 (50 + 10) = 100 × 60 = 6000 km Â
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