Shanghai World Expo billboard is trapezoidal in shape. The upper bottom is 8 meters long, the lower bottom is 11 meters long, and the height is 4 meters. 0.5 kg of paint per square meter is 15 yuan per kilogram of paint. How much does it cost to paint this billboard?
一块上海世博会广告牌是梯形形状．上底长8米，下底长11米，高4米，每平方米涂油漆0.5千克，每千克油漆15元，漆这个广告牌需要多少元？
<gadget id="calculator">8 + 11</gadget>
<output>19</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">19 * 2 * 0.5 * 15</gadget>
<output>285</output>

<result>285</result>