Notes from the SAT

QOD2015_0415 (1)
As Easy as A – B – C
April 16, 2015
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Notes from the SAT

QOD2015_0417
Explanation
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 (D) zx (E) 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, 100−80=20 Where y = 80 and z = 20. So, rewriting it again using the variables, we have: x−y=z Solving for y: y=x−z

The correct answer is (B).

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