A book has n consecutive pages torn out. Suppose A is the last numbered page before the torn-out section and B is the first numbered page following the torn out section. Find a formula for n in terms of A and B.

The answer is n = (a-b) - 1 because when you subtract a-b, you get almost the number of pages, but as you are counting the page b which has is not torn out, you must subtract 1 to get the correct answer if you plugged in a variable