A street billboard is an isosceles trapezoid, the upper base is 4 meters, the lower base is 6 meters, and the height is 2.5 meters. If the front and back sides are painted, how many square meters is the painted area?
一块街头广告牌是个等腰梯形，上底是4米，下底是6米，高是2.5米，在它的正反两面刷油漆，刷油漆的面积是多少平方米？
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">2.5 / 2</gadget>
<output>1.25</output>

<gadget id="calculator">10 * 1.25 * 2</gadget>
<output>25</output>

<result>25</result>