Huangcun planted 4,280 trees last year, 3,080 the year before last, and 4,640 trees this year. How many trees were planted each year on average in the past three years?
黄村去年种树4280株，前年种树3080株，今年种树4640株，三年中平均每年种树多少株？
<gadget id="calculator">4_280 + 3_080 + 4_640</gadget>
<output>12_000</output>

<gadget id="calculator">12_000 / 3</gadget>
<output>4_000</output>

<result>4_000</result>