A rectangular rice field is 50 meters wide, and its length is 20 meters less than twice its width. What is the area of this rice field in square meters?
一块长方形水稻田，宽是50米，长比宽的2倍少20米，这块水稻地的面积是多少平方米？
<gadget id="calculator">50 * 2</gadget>
<output>100</output>

<gadget id="calculator">100 - 20</gadget>
<output>80</output>

<gadget id="calculator">80 * 50</gadget>
<output>4_000</output>

<result>4_000</result>