The area of a trapezoid is 180 square centimeters, the upper base is 6 centimeters, the height is 20 centimeters, how many centimeters is the lower base?
一个梯形面积是180平方厘米，上底是6在厘米，高是20厘米，下底是多少厘米？
<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">180 * (1/10)</gadget>
<output>18</output>

<gadget id="calculator">18 - 6</gadget>
<output>12</output>

<result>12</result>