There is an approximately trapezoidal orchard, the sum of the upper base and the lower base is 500 meters, and the height is 60 meters. Calculated by spraying 2.9 kilograms of pesticides per hectare. How many kilograms of pesticides are needed to spray this orchard once?
有一个近似梯形的果园，上底加下底的和是500米，高是60米．按每公顷喷洒农药2.9千克计算．给这个果园喷洒一次农药，一共需要多少千克农药？
<gadget id="calculator">60 / 2 / 10_000</gadget>
<output>3/1_000 = around 0.003</output>

<gadget id="calculator">500 * (3/1_000)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) * 2.9</gadget>
<output>4.35</output>

<result>4.35</result>