A rectangular playground is 50 meters long and 20 meters wide. The students run around the playground once. How many meters do they need to run?
一个长方形的操场，长50米，宽20米，同学们围绕操场跑了1圈，要跑多少米？
<gadget id="calculator">50 + 20</gadget>
<output>70</output>

<gadget id="calculator">70 * 2</gadget>
<output>140</output>

<result>140</result>