The area of a trapezoid is 24 square decimeters, the upper base is 5 decimeters, and the height is 4 decimeters. How many decimeters is the lower base of this trapezoid?
一个梯形的面积是24平方分米，上底是5分米，高是4分米，这个梯形的下底是多少分米？
<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>