Given:
Scott can run 20 km in 85 minutes.
To find:
How long will it take Scott to run 52 km?
Solution:
Let us consider x be the number of minutes it will take him to run 52 km.
We know that,

By using this formula, we get
...(i)
...(ii)
On equating (i) and (ii), we get



On dividing both sides by 20, we get


Hence, it will take 221 minutes to run 52 km.