Uncle Zhang has a parallelogram of land, 4 meters high and 16 meters long at the bottom. After Uncle Zhang reduced the bottom of a line by 6 meters, the land became a trapezoid. So what is the area of this trapezoidal land?
张伯伯有一块平行四边形的土地，高4米，底长16米．张伯伯将一条底减少6米后，这块土地变成了梯形．那么这块梯形土地的面积是多少？
<gadget id="calculator">16 - 6</gadget>
<output>10</output>

<gadget id="calculator">10 + 16</gadget>
<output>26</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">26 * 2</gadget>
<output>52</output>

<result>52</result>