It is known that the area of the trapezoid is 60 square centimeters, the height is 12 centimeters, and the bottom is 4 centimeters. How many centimeters is the top bottom?
已知梯形的面积是60平方厘米，高是12厘米，下底是4厘米，求上底是多少厘米？
<gadget id="calculator">2 / 12</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">60 * (1/6)</gadget>
<output>10</output>

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

<result>6</result>