A trapezoidal billboard, the upper base is 9 meters, the lower base is 12.8 meters, and the height is 6 meters. If you want to paint this billboard, you need 0.6 kilograms of paint per square meter. How many kilograms of paint are needed?
一块梯形广告牌，上底是9米，下底是12.8米，高是6米，如果要给这块广告牌刷油漆，每平方米用油漆0.6千克，共需多少千克油漆？
<gadget id="calculator">9 + 12.8</gadget>
<output>21.8</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">21.8 * 3 * 0.6</gadget>
<output>39.24</output>

<result>39.24</result>