A new notepad has x pages. After y pages are used, there are z pages left. What is y in terms of x and z?
(A) x + z
(B) x - z
(C) z - x
This question requires that we develop an expression relating y to the other variables. We can use test numbers to make sure our algebra is correct.
We are told that a notepad contains x pages (which we can define to be any number, let us call it 100) and that when y pages are used, there are z pages remaining. Well, this says that if we use 80 pages, for example, we have 20 pages left. Therefore we can write the expression as,
Where y = 80 and z = 20. So, rewriting it again using the variables, we have:
Solving for y:
The correct answer is (B).