The area of a trapezoid is 90 square centimeters, the upper base is 20 cm, the lower base is 25 cm, and the height is in cm.
一个梯形的面积是90平方厘米，上底是20厘米，下底是25厘米，高是多少厘米．
<gadget id="calculator">20 + 25</gadget>
<output>45</output>

<gadget id="calculator">2 / 45</gadget>
<output>2/45 = around 0.044444</output>

<gadget id="calculator">90 * (2/45)</gadget>
<output>4</output>

<result>4</result>