If the area of a trapezoid is 90 square centimeters and the height is 30 centimeters, what is the sum of its upper and lower bases in centimeters?
如果一个梯形的面积是90平方厘米，高是30厘米，则它的上下底之和是多少厘米
<gadget id="calculator">2 / 30</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">90 * (1/15)</gadget>
<output>6</output>

<result>6</result>