The area of the trapezoid is 16.8 square centimeters, the height is 3 centimeters, the bottom is 8 centimeters, and the top is in centimeters.
梯形的面积是16.8平方厘米，高是3厘米，下底是8厘米，上底是多少厘米．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">16.8 * (2/3)</gadget>
<output>11.2</output>

<gadget id="calculator">11.2 - 8</gadget>
<output>3.2</output>

<result>3.2</result>