The area of a trapezoid is 24dm**2, the upper base is 5dm, the height is 4dm, how many decimeters is the lower base?
一个梯形的面积是24dm**2，上底是5dm，高是4dm，下底是多少分米？
<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">24 * (1/2)</gadget>
<output>12</output>

<gadget id="calculator">12 - 5</gadget>
<output>7</output>

<result>7</result>