A trapezoidal land, the upper base is 13 meters long, the lower base is 12 meters long, and the height is 12 meters. If 20 cabbages are planted per square meter, how many cabbages are planted in this land?
一块梯形地，上底长13米，下底长12米，高12米．如果每平方米栽白菜20棵，这块地共栽白菜多少棵？
<gadget id="calculator">12 + 13</gadget>
<output>25</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">25 * 6 * 20</gadget>
<output>3_000</output>

<result>3_000</result>