The length of a rectangle is 20 cm and the width is 4 cm less than the length. What is the area of the rectangle in square centimeters?
一个长方形的长是20厘米，宽比长少4厘米，这个长方形的面积是多少平方厘米
<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">20 * 16</gadget>
<output>320</output>

<result>320</result>