Answer:
Sue is 60 miles ahead of Clint
Sue travel at 40 mph while Clint travels at 60 mph. In the first hour, sue would have travelled 100 miles while Clint travelled 60 miles. In the second hour, Sue travelled a total distance of 140 miles and Clint 120 miles. In the third hour, Sue would have travelled 180 miles while Clint 180 miles. So they meet in the third hour.
Therefore it takes 3 hours for Clint to catch up with Sue
Hope this helps!