For a trapezoid, the lower base is twice as long as the upper base. If the length of the upper and lower bases remains the same, but the height increases by 4 cm, the area increases by 24 cm2. What is the length of the upper base of the original trapezoid in cm?
一个梯形，下底是上底的2倍，如果上下底长度不变，高增加4厘米，面积就增加24平方厘米，那么原来梯形的上底长是多少厘米
<gadget id="calculator">48 / 2</gadget>
<output>24</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">24 * (1/3)</gadget>
<output>8</output>

<result>8</result>