The area of the trapezoid is 12cm**2, the upper base is 2cm, the lower base is 4cm, and the height is cm.
梯形的面积是12cm**2，上底2cm，下底是4cm，高是多少cm．
<gadget id="calculator">2 + 4</gadget>
<output>6</output>

<gadget id="calculator">2 / 6</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 * (1/3)</gadget>
<output>4</output>

<result>4</result>