The sum of the upper and lower bases of a trapezoid is 18 cm and its area is 270 cm2. What is its height in cm?
一个梯形上、下底的和是18厘米，面积是270平方厘米，它的高是多少厘米．
<gadget id="calculator">2 / 18</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">270 * (1/9)</gadget>
<output>30</output>

<result>30</result>