The upper base of a trapezoid is 28 decimeters, the lower base is 30 decimeters, and the height is 16 decimeters. What is its area?
一个梯形的上底是28分米，下底是30分米，高是16分米，它的面积是多少平方分米？
<gadget id="calculator">28 + 30</gadget>
<output>58</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">58 * 8</gadget>
<output>464</output>

<result>464</result>