There is a trapezoidal vegetable field, the upper base is 15 meters, 5 meters shorter than the lower base, and the height is 60 meters. Last year, a total of 10,500 kilograms of cabbage was harvested. How many kilograms of cabbage were harvested on average per square meter?
有一块梯形菜地，上底是15米，比下底短5米，高是60米，去年共收白菜10500千克，平均每平方米收白菜多少千克？
<gadget id="calculator">15 + 15 + 5</gadget>
<output>35</output>

<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">35 * 30</gadget>
<output>1_050</output>

<gadget id="calculator">10_500 / 1_050</gadget>
<output>10</output>

<result>10</result>