A trapezoidal orchard with an upper base of 300 meters, a lower base of 500 meters and a height of 100 meters. How many hectares does this orchard cover?
一个梯形果园，上底300米，下底500米，高100米．这个果园占地多少公顷？
<gadget id="calculator">300 + 500</gadget>
<output>800</output>

<gadget id="calculator">100 / 2 / 10_000</gadget>
<output>1/200 = around 0.005</output>

<gadget id="calculator">800 * (1/200)</gadget>
<output>4</output>

<result>4</result>