A decorative sign in a supermarket is an isosceles trapezoid, its upper base is 16 meters, its lower base is 22 meters, and its height is 3 meters. To paint one side of this decorative sign, 0.5 kilograms of paint is needed per square meter. How many kilograms of paint are needed in total?
一个超市的装饰牌是等腰梯形，它的上底是16米，下底是22米，高是3米．用油漆刷这块装饰牌的一面，每平方米需要用0.5千克油漆，一共需要多少千克油漆？
<gadget id="calculator">16 + 22</gadget>
<output>38</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">38 * (3/2)</gadget>
<output>57</output>

<gadget id="calculator">57 * 0.5</gadget>
<output>28.5</output>

<result>28.5</result>