The perimeter of a rectangular square is 600 meters, the width is 40 meters, how many meters is the length? (Solution of column equation)
一个长方形广场的周长是600米，宽是40米，长是多少米？(列方程解)
<gadget id="calculator">40 * 2</gadget>
<output>80</output>

<gadget id="calculator">600 - 80</gadget>
<output>520</output>

<gadget id="calculator">520 / 2</gadget>
<output>260</output>

<result>260</result>