Photo by Kaboompics .com on Pexels.com

This series is designed to help you step up your Data Sufficiency practice while we all spend a little extra time at home during the coronavirus situation; I’m going to publish one practice Data Sufficiency question each day! You can choose to do all of them, or none of them. 

Click on the tag “Social Distancing DS Challenge” at the bottom of this post to see all of the questions in this series! 

And remember to take whatever precautions you need to stay healthy over the next few weeks! 

Question #20

If x – y = z, what is the value of y?

(1) x = 7

(2) z = x + 4

 Explanation

Statement (1) is insufficient because, if we plug in x = 7 we are left with: 7 – y = z … and we still are unable to solve for y‘s value.

Let’s try plugging in statement (2): x – y = z … x – y = (x + 4) … -y = 4 … y = -4:  Statement (2) alone is sufficient! The correct answer is (B).