The area of a trapezoid is 25dm**2, the height is 5 decimeters, and the upper base is 4 decimeters. How many decimeters is the bottom.
一个梯形的面积是25dm**2，高是5分米，上底是4分米．下底是多少分米．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 * (2/5)</gadget>
<output>10</output>

<gadget id="calculator">10 - 4</gadget>
<output>6</output>

<result>6</result>