In a trapezoidal sweet potato field, the upper base is 12.5 meters, the lower base is twice as long as the upper base, and the height is 8.6 meters. A total of 1290 kg of sweet potatoes are harvested. How many kilograms of sweet potatoes are harvested on average per square meter?
一块梯形番薯地，上底是12.5米，下底是上底的2倍，高8.6米，一共收番薯1290千克，平均每平方米收番薯多少千克？
<gadget id="calculator">12.5 * 2</gadget>
<output>25</output>

<gadget id="calculator">12.5 + 25</gadget>
<output>37.5</output>

<gadget id="calculator">8.6 / 2</gadget>
<output>4.3</output>

<gadget id="calculator">37.5 * 4.3</gadget>
<output>161.25</output>

<gadget id="calculator">1_290 / 161.25</gadget>
<output>8</output>

<result>8</result>