The area of a trapezoid is 9 square meters, the height is 3 meters, the upper base is 2.8 meters, and the lower base is how many meters.
一个梯形的面积是9平方米，高是3米，上底是2.8米，下底是多少米．
<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 - 2.8</gadget>
<output>3.2</output>

<result>3.2</result>