After subtracting 5 centimeters from the length and 2 centimeters from the width, a square is obtained. The area of this square is 31 square centimeters less than the area of the original rectangle. What is the area of the original rectangle?
把长方形的长去掉5厘米，宽去掉2厘米后，得到一个正方形，这个正方形的面积比原长方形的面积减少31平方厘米，原长方形的面积是多少？
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<result>40</result>