A parallelogram-shaped vegetable field has a base of 15 meters and a height of 4 meters, and a total of 1080 kilograms of vegetables can be harvested. How many kilograms of vegetables can be harvested on average per square meter of this field?
一块平行四边形的菜地，它的底是15米，高是4米，共收蔬菜1080千克，这块地平均每平方米收蔬菜多少千克？
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<gadget id="calculator">1_080 / 60</gadget>
<output>18</output>

<result>18</result>