A trapezoidal land, the upper base is 20 meters shorter than the lower base, the lower base is 46 meters, and the height is half of the upper base, what is the area of the land?
一梯形地，上底比下底短20米，下底是46米，高是上底的一半，这块地的面积是多少．
<gadget id="calculator">46 - 20</gadget>
<output>26</output>

<gadget id="calculator">26 + 46</gadget>
<output>72</output>

<gadget id="calculator">26 / 13</gadget>
<output>2</output>

<gadget id="calculator">13 / 2</gadget>
<output>13/2 = around 6.5</output>

<gadget id="calculator">72 * (13/2)</gadget>
<output>468</output>

<result>468</result>