The area of a trapezoid is 38 square meters, the height is 4 meters, the upper base is 9.1 meters, and the lower base is how many meters.
一个梯形的面积是38平方米，高4米，上底9.1米，下底是多少米．
<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">38 * (1/2)</gadget>
<output>19</output>

<gadget id="calculator">19 - 9.1</gadget>
<output>9.9</output>

<result>9.9</result>