The area of a trapezoid is 20.5cm**2, the upper base is 6cm, the lower base is 10.4cm, what is the height?
一个梯形的面积是20.5cm**2，上底是6cm，下底是10.4cm，高是多少．
<gadget id="calculator">6 + 10.4</gadget>
<output>16.4</output>

<gadget id="calculator">2 / 16.4</gadget>
<output>0.121951</output>

<gadget id="calculator">20.5 * 0.121951</gadget>
<output>2.499996</output>

<result>2.499996</result>