The upper base of a trapezoid is 24 cm, the lower base is 16 cm, and the height is 1 cm. What is the area?
一个梯形的上底是24厘米，下底是16厘米，高是1厘米，面积是多少．
<gadget id="calculator">24 + 16</gadget>
<output>40</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 * (1/2)</gadget>
<output>20</output>

<result>20</result>