The perimeter of the rectangle is 50 decimeters and the length is 18 decimeters. What is the area of the rectangle?
长方形的周长是50分米，长是18分米，这个长方形的面积是多少平方分米？
<gadget id="calculator">50 / 2</gadget>
<output>25</output>

<gadget id="calculator">25 - 18</gadget>
<output>7</output>

<gadget id="calculator">18 * 7</gadget>
<output>126</output>

<result>126</result>