The height of a trapezoid is 8 cm, the lower base is 9 cm, and the area is 56 cm2. What is the upper base in cm?
一个梯形的高是8厘米，下底是9厘米，面积是56平方厘米，它的上底是多少厘米．
<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">56 * (1/4)</gadget>
<output>14</output>

<gadget id="calculator">14 - 9</gadget>
<output>5</output>

<result>5</result>