Summing it up:
The worm starts to eat here [1.] and ends here [.3] so it eats the front cover of book 1, all of book 2 and the back cover of book 3: 0.25 + 2.5 + 0.25 = 3.

Shelf design: [][][] where each [] is a book. The key word here is “respectively”. Therefore we assume the following:
The books are arrange as such:
3] with the side cover facing outside. Because of this the pages go first <- last (ie: since you are facing the books the pages start at 1 at the right and the last at the left).

Shelf design: [][][] where each [] is a book. The key word here is “respectively”. Therefore we assume the following:
The books are arrange as such:
3] with the side cover facing outside. Because of this the pages go first <- last (ie: since you are facing the books the pages start at 1 at the right and the last at the left).

Shelf design: [][][] where each [] is a book. The key word here is “respectively”. Therefore we assume the following:
The books are arrange as such:
3] with the side cover facing outside. Because of this the pages go first <- last (ie: since you are facing the books the pages start at 1 at the right and the last at the left).

that’s very tricky to catch….nice one