The area of a trapezoid is 16 square meters, the upper base is 30 decimeters, the lower base is 50 decimeters, and the height is decimeters.
一个梯形的面积是16平方米，上底是30分米，下底是50分米，高是多少分米．
<gadget id="calculator">30 + 50</gadget>
<output>80</output>

<gadget id="calculator">2 / 80</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">16 * 100 * (1/40)</gadget>
<output>40</output>

<result>40</result>