There is a trapezoidal vegetable field, the upper base is 52 meters, the lower base is 48 meters, and the height is 30 meters. If 28 kilograms of cabbage are harvested per square meter, how many kilograms of cabbage are harvested in this land?
有一块梯形的菜地，上底是52米，下底是48米，高是30米．如果每平方米收28千克白菜，这块地一共收白菜多少千克？
<gadget id="calculator">52 + 48</gadget>
<output>100</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">100 * 15 * 28</gadget>
<output>42_000</output>

<result>42_000</result>