A trapezoid, the sum of the upper and lower bases is 8cm, and the height is 5cm, what is its area in cm2?
一个梯形，上底和下底的和是8cm，高是5cm，它的面积是多少c㎡．
<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>