A cabbage field is trapezoidal in shape, its upper base is 9 meters, its lower base is 12 meters, and its height is 18 meters. If each cabbage occupies an average area of 9 square decimeters, how many cabbages are there in total?
一块白菜地形状是梯形，它的上底是9米，下底是12米，高是18米，如果平均每棵白菜占地9平方分米，这块地里一共有白菜多少棵？
<gadget id="calculator">9 + 12</gadget>
<output>21</output>

<gadget id="calculator">18 / 2 / 0.09</gadget>
<output>100</output>

<gadget id="calculator">21 * 100</gadget>
<output>2_100</output>

<result>2_100</result>