Hello there! Shelly ran D) 5/10 more miles than Ben.
To find the difference between the two runner's distances, subtract the smaller distance from the greater distance.
8/10 - 3/10 = 5/10
Since there is a difference of 5/10, this means Shelly ran 5/1 more miles.
I hope this helps, & have a great rest of your day! :)