A rectangular flowerbed has a width of 15 meters and a circumference of 90 meters. What is its area in square meters?
一个长方形的花圃，宽是15米，周长是90米，它的面积是多少平方米？
<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<gadget id="calculator">30 * 15</gadget>
<output>450</output>

<result>450</result>