find the common denominators. for the miles 5 and 3 go into 15. so 2/5 times 3 is 6/15. and 2/3 times 5 is 10/15. for the hours 5 and 9 go into 45. 1/5 times 9 is 9/45. and 2/9 times 5 is 10/45. so Susan ran 6/15 of a mile in 9/45 of an hour. and Kim ran 10/15 of a mile in 10/45 of an hour.
so Kim ran 3 miles in an hour. Susan ran 2 miles in an hour.