A trapezoid, the sum of the upper and lower bases is 8 meters, and the height is 5 meters, what is its area in meters**2.
一个梯形，上底与下底的和是8米，高是5米，它的面积是多少米**2．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">8 * (5/2)</gadget>
<output>20</output>

<result>20</result>