The width of the rectangle is 15 cm, and the length is twice the width. What is the area of the rectangle?
长方形的宽是15cm，长是宽的2倍，长方形的面积是多少平方厘米？
<gadget id="calculator">15 * 2 * 15</gadget>
<output>450</output>

<result>450</result>