A trapezoidal vegetable field has an area of 1000 square meters, the upper base is 40 meters, and the height is 8 meters. How many meters is the lower base?
一块梯形菜地，面积是1000平方米，上底是40米，高是8米，下底是多少米？
<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1_000 * (1/4)</gadget>
<output>250</output>

<gadget id="calculator">250 - 40</gadget>
<output>210</output>

<result>210</result>