# GRE Quantitative Practice, Standard Multiple-Choice

*Question 4*

In a certain parallelogram, the size of one interior angle exceeds that of another interior angle by *D* degrees. Which of the following expressions represents the degree measure of the smaller angle?

- 90 –
*D* - 180 –
- 120 –
*D* - 90 –
- 180 –
*D*

## Explanatory Answer

Let *x* equal the degree measure of the smaller angle, and let (*x* + *D*) equal the degree measure of the larger angle. The two angles are by definition supplementary, which means that their degree measures total 180:

x+ (x+D) = 180

Solving for *x* yields the expression in choice (D), which is the correct answer.