The perimeter of a rectangular flowerbed is 1500 meters, and the known length is 500 meters. What is the area of this flowerbed in hectares?
一块长方形花圃的周长是1500米，已知长是500米，这块花圃的面积是多少公顷？
<gadget id="calculator">1_500 / 2</gadget>
<output>750</output>

<gadget id="calculator">750 - 500</gadget>
<output>250</output>

<gadget id="calculator">250 / 10_000</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">500 * (1/40)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>