A wheat field has 50 hectares, and the harvester has harvested 10 hectares in 5 hours. According to this calculation, how many hours will the harvester have left? (proportional solution)
一块麦地有50公顷，收割机5小时收割完了10公顷，照这样计算，收割机余下的还要几小时？(比例解)
<gadget id="calculator">50 - 10</gadget>
<output>40</output>

<gadget id="calculator">5 * 40</gadget>
<output>200</output>

<gadget id="calculator">200 / 10</gadget>
<output>20</output>

<result>20</result>