The length of a rectangular playground is 400 meters and the width is 80 meters. What is the length of the playground?
一个长方形的操场一周的长度是400米，宽是80米，操场的长是多少米？
<gadget id="calculator">400 / 2</gadget>
<output>200</output>

<gadget id="calculator">200 - 80</gadget>
<output>120</output>

<result>120</result>