A court is 20 meters long and 10 meters wide, what is the circumference of half the court?
一个球场长20米，宽10米，那么半个球场的周长是多少米？
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 + 10</gadget>
<output>20</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<result>40</result>