The upper base of the trapezoid is 2.4 meters, which is 8 decimeters less than the lower base, and the height is half of the lower base. Find the area of this trapezoid?
梯形的上底为2.4米，比下底少8分米，高是下底的一半，求这个梯形的面积？
<gadget id="calculator">2.4 * 10</gadget>
<output>24</output>

<gadget id="calculator">24 + 8</gadget>
<output>32</output>

<gadget id="calculator">32 + 24</gadget>
<output>56</output>

<gadget id="calculator">32 / 2 / 2</gadget>
<output>8</output>

<gadget id="calculator">56 * 8</gadget>
<output>448</output>

<result>448</result>