There is an experimental field for testing new rice products, with an area of 40 mu in total. One part is planted with new varieties, and the other part is planted with old varieties (the planting area is not equal), so as to facilitate the comparison of results. The old variety yielded 500 kg per mu; 75% of the new varieties were unsuccessful, yielding 400 kg per mu, but the other 25% were successful, yielding 800 kg per mu. If the yields of the new and old varieties are the same, how many kilograms of rice will be produced in this experimental field?
有一块用于实验新产品水稻的试验田，面积共40亩，一部分种植新品种，另一部分种植旧品种(种植面积不相等)，以方便比较成果．旧品种每亩产500千克；新品种中有75%都没有成功，每亩产400千克，但是另外25%实验成功，每亩产800千克．若新、旧品种的产量相同，那么，这块试验田共产水稻多少千克．
<gadget id="calculator">300 + 200 + 500</gadget>
<output>1_000</output>

<gadget id="calculator">20_000 / 1_000</gadget>
<output>20</output>

<gadget id="calculator">40 - 20</gadget>
<output>20</output>

<gadget id="calculator">20 * 500 * 2</gadget>
<output>20_000</output>

<result>20_000</result>