A rectangular vegetable field is 30 meters long and 20 meters wide. A total of 9,000 kilograms of cabbage is harvested in this vegetable field. How many kilograms of cabbage are harvested on average per square meter?
一块长方形菜地长30米，宽20米，在这块菜地里共收获白菜9000千克，平均每平方米收获白菜多少千克？
<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">9_000 / 600</gadget>
<output>15</output>

<result>15</result>