Thank you for the opportunity to help you with your question!
The distance from home is 3 3/4 mile and we are told that he biked 1 1/10 . this means we find the difference between the distance from home to library and the distance he biked when he realised that he had forgotten a book
we subtract 3, 3/4 from 1 ,1/10
we get 2 ,13/20 or 2.65 miles
To find the total distance we add this to 3 3/4 because we are told he went back from home to libray after taking the forgotten book
3 3/4+2, 13/20=6, 2/5
Please let me know if you need any clarification. I'm always happy to answer your questions.