You are biking to the library. When you are 75% of the way there, you realize you forgot a book. So you turn around and head back. When you are of the way back you realize you don’t need the book, so you turn around again and bike 3.2 miles back to the library. How far do you live from the library?
Could you rewrite the fourth sentence?
This is the part I don't understand: "When you are of the way back you realize you don’t need the book".