Hi M7MBA,

We're told that a SQUARE has the coordinates: (X, Y), (20, 20), (20, 5) and (X, 5). We're asked for the AREA of that square.

To start, you would likely find it useful to draw a quick sketch of what you know. You can graph the points (20,20) and (20,5). Those two co-ordinates COULD be the side of the square OR they could be the diagonal of the square, so a little more work is needed to know for sure. Consider the point (X, 5) along with those 2 co-ordinates. Wherever that third point is located, the angle created among those 3 points will create a RIGHT ANGLE since (X, 5) and (20,5) create a horizontal line and (20,5) and (20,20) create a vertical line. Thus, we now know that (20,20 and (20,5) represent one side of the square.

That side length is 20 - 5 = 15.

With that side length, we can answer the given question. The area of the square will be 15^2 = 225.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich