A trapezoidal piece of land has an upper base of 64 meters, a lower base of 56 meters, and a height of 30 meters. What is its area in hectares?
一块梯形土地，上底是64米，下底是56米，高是30米，它的面积是多少公顷．
<gadget id="calculator">64 + 56</gadget>
<output>120</output>

<gadget id="calculator">1 * 10_000</gadget>
<output>10_000</output>

<gadget id="calculator">30 / 2 / 10_000</gadget>
<output>3/2_000 = around 0.0015</output>

<gadget id="calculator">120 * (3/2_000)</gadget>
<output>9/50 = around 0.18</output>

<result>9/50 = around 0.18</result>