Subtracting whole numbers does not include subtracting negative numbers, whereas when subtracting integers you can include negative numbers.
I think it’s 1 feet because the tops are touching you have to spread the bottoms apart so it can touch
This is only my opinion. I could be wrong.
My guess is:
Somebody else used that book before you, maybe last year or
the year before, and it was somebody who didn't mind writing
in his book.
One day he didn't have time to write down the homework in his
assignment notebook, so he just circled the homework problems
in his textbook.
