A cabbage field is trapezoidal in shape. Its upper base is 8 meters, its lower base is 12 meters, and its height is 9 meters. If each cabbage covers an area of 9 square decimeters on average, how many cabbages are there in this field?
一块白菜地的形状是梯形．它的上底是8米，下底是12米，高是9米．如果平均每棵白菜占地9平方分米，这块地里一共有多少棵白菜？
<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<gadget id="calculator">9 / 2 / 0.09</gadget>
<output>50</output>

<gadget id="calculator">20 * 50</gadget>
<output>1_000</output>

<result>1_000</result>