Question

a man runs a distance of 197.5 km in 200 minutes and he reduced his speed by 5 kmph in every 30 minutes. how much distance he will cover in 1 hour of his journey

Answer 1

in your problem statement the man is running at about 59 km/hr

you probably want to restate

Answer 2

Your data makes no sense!
How can he "run" almost 200 km in about 3 hours???

Fix your question before so it can be answered realistically.