Well, Tim ran 4/8 miles and Lucy ran 7/10. To solve this, i am changing the fractions to decimals.
4/8 as a decimal is 0.5
7/10 as a decimal is 0.7
So as you can see, 0.7 is bigger. So Lucy ran farther. But if you approximate the decimals, then they both run the same miles because when the two decimals are approximated, you get 1. Hope i helped. Have a nice day.