A rectangle has a perimeter of 60 meters and its length is 4 meters more than its width. What is the area of the rectangle?
一个长方形的周长为60米，长比宽多4米，这个长方形的面积是多少．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 4</gadget>
<output>26</output>

<gadget id="calculator">26 / 2</gadget>
<output>13</output>

<gadget id="calculator">13 + 4</gadget>
<output>17</output>

<gadget id="calculator">17 * 13</gadget>
<output>221</output>

<result>221</result>