The area of a trapezoid is 18 square decimeters, the height is 3 decimeters, the upper base is 5 decimeters, and the lower base is how many decimeters.
一个梯形的面积是18平方分米，高3分米，上底5分米，下底多少分米．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">18 * (2/3)</gadget>
<output>12</output>

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

<result>7</result>