A pedestrian has to walk 100 km. He walked 4 hours at a speed of 5 km / h. How many kilometers is left for him to walk?

1) Find how many kilometers a pedestrian has traveled:
4 * 5 = 20
20 km walked by a pedestrian
2) Find how many kilometers the pedestrian has to go:
100-20 = 80
Answer: 80km

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