A trapezoidal rice field has an upper base of 68 meters, a lower base of 112 meters, and a height of 45 meters. A total of 8.1 tons of rice is harvested. How many kilograms of rice are harvested per square meter on average?
一块梯形稻田，上底68米，下底112米，高45米，一共收水稻8.1吨，平均每平方米收水稻多少千克？
<gadget id="calculator">112 + 68</gadget>
<output>180</output>

<gadget id="calculator">45 / 2</gadget>
<output>45/2 = around 22.5</output>

<gadget id="calculator">180 * (45/2)</gadget>
<output>4_050</output>

<gadget id="calculator">1_000 / 4_050</gadget>
<output>20/81 = around 0.246914</output>

<gadget id="calculator">8.1 * (20/81)</gadget>
<output>2</output>

<result>2</result>