Target Test Prep Sample GRE Quantitative Comparison Problem

Solution:

We must determine the value of z to solve for both Quantity A and Quantity B.  We are given two equations:  2x + 2y = –4 and  $\frac{\mathrm{z}}{2}=\mathrm{x}+\mathrm{y}$.

With these two equations we can produce a unique value for z.  The first equation can be reduced to

x + y = –2. We can substitute –2 for x + y in equation two to yield  $\frac{\mathrm{z}}{2}=-2\to \mathrm{z}=-4$. Since z is negative, z² is greater than z. 

Thus, Quantity B is greater than Quantity A.