A man moving with a speed of 5 m/s sees a dog at a distance of 300m. he throws a stone at the dog, so the dog starts chasing him. If the dog catches up with the man in 20 seconds, find the speed at which the dog chased the man.
1
5 m/s
2
10 m/s
3
15 m/s
4
20 m/s
5
25 m/s