The area of a trapezoid is 36 square meters, the height is 9 meters, and the upper base is 3 meters. What is its lower base?
一个梯形的面积是36平方米，高是9米，上底是3米，它的下底是多少．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">36 * (2/9)</gadget>
<output>8</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<result>5</result>