# GMAT Quantitative Practice, Problem Solving

*Question 4*

If *p* Ο *q* = *p*(*q* – *p*), which of the following specific operations yields 2*p* – 4 ?

- 2
*p*Ο 2 *p*Ο 2- 2
*p*Ο*p* - 2 Ο 2
*p* - 2 Ο
*p*

## Explanatory Answer

This problem involves a *defined operation* and is essentially an exercise in algebraic substitution. For each answer choice, "plug" the given values into the expression *p*(*q* – *p*).

You can eliminate the first three listed operations because each one yields a quadratic expression containing a *p*^{2} term. The operation given in choice (E) is the one that yields 2*p* – 4:

p(q–p) = 2(p– 2) = 2p– 4

The correct answer is (E).