You divide the width of the book by the number of sheets of paper in order to get the thickness of each of the pieces of paper.
Let's take 6, 12 as our first example. We're trying to find out the difference between the two...take 12 minus 6 and you get a difference of 6 between them.
Now the first problem, 4, -17...put the larger one first and subtract the smaller one. 4 minus negative 17 is the same as 4 plus 17 which is 21.
23-8 is 15, of course.
-1-14 is -15, but the difference between something can't be negative, so it's just 15.
18-(-3) = 18+3 = 21.
Integers are set of whole numbers <em>and </em>their counterparts, for example:
..., -3, -2, -1, 0, 1, 2, 3, ...
If the given integer is below 0, then its opposite will be positive. Let's check it on the example:
Opposite of 5 is -5 (so Cindy is right here)
But opposite of -5 is 5 (so she's wrong)