Linear Equation 10

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A man covers a distance of 15 km in 3 hours, partly by walking and partly be running.
If he walks at 3 km/h and runs at 9 km/h, find the distance covered by running.

Solution:

Let the distance covered by running be x km

Therefore, distance covered by walking (15 - x) km

Therefore, Time taken to cover x km by running = x / 9 hr [since, time = distance / speed ]

and, time taken to cover (15 - x) km by walking = (15 - x) / 3 hr

since, the man covers the total distance in 3 hrs

Therefore, x / 9 + (15 - x) / 3 = 3 [ As total time taken = 3 hrs ]

on solving the above equation, we have

=> x = 9

Therefore, Distance covered by running = 9 km

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