The area of a trapezoid is 80cm**2, its upper base is 4cm, and its height is 16cm. What is the lower base of this trapezoid?
一个梯形的面积是80cm**2，它的上底是4cm，高是16cm，这个梯形的下底是多少．
<gadget id="calculator">2 / 16</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">80 * (1/8)</gadget>
<output>10</output>

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

<result>6</result>