There is a trapezoidal cotton field, the upper base is 500 meters, the height is 400 meters, and the lower base is 700 meters. If each square meter can produce 0.25 kg of lint per year, how many tons of lint can this cotton field produce per year?
有一块梯形的棉花地，上底是500米，高是400米，下底是700米，如果每平方米一年可以产皮棉0.25千克，这块棉花地一年可产皮棉多少吨？
<gadget id="calculator">500 + 700</gadget>
<output>1_200</output>

<gadget id="calculator">400 / 2</gadget>
<output>200</output>

<gadget id="calculator">0.25 / 1_000</gadget>
<output>0.00025</output>

<gadget id="calculator">1_200 * 200 * 0.00025</gadget>
<output>60</output>

<result>60</result>