A trapezoid has an upper base of 3.4 cm, a lower base of 4.6 cm, and a height of 5 cm. What is the area of the trapezoid?
一个梯形，上底是3.4厘米，下底是4.6厘米，高是5厘米，则这个梯形的面积是多少．
<gadget id="calculator">3.4 + 4.6</gadget>
<output>8</output>

<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>