The perimeter of a rectangular piece of land is 1800 meters, the length is 600 meters, and how many meters is the width? How many.
一块长方形地的周长是1800米，长是600米，宽是多少米？多少．
<gadget id="calculator">1_800 / 2</gadget>
<output>900</output>

<gadget id="calculator">900 - 600</gadget>
<output>300</output>

<result>300</result>